Editing GCHQ (section)

==History==
{{See also|Ultra (cryptography)|l1=Second World War activities of GC&CS referred to as 'Ultra'}}

===World War I===
During the First World War, the [[British Army]] and [[Royal Navy]] had separate signals intelligence agencies, [[MI1b]] and [[NID25]] (initially known as Room 40) respectively.<ref>{{cite book |first=Paul |last=Gannon |title=Inside Room 40: The Codebreakers of World War I |publisher=Ian Allan Publishing |year=2011 |isbn=978-0-7110-3408-2}}</ref><ref>Johnson, 1997, p. 27</ref> 

===Interwar Period===
{{anchor|Government Code and Cypher School}}
In 1919, the Cabinet's Secret Service Committee, chaired by [[Lord Curzon]], recommended that a peacetime codebreaking agency should be created, a task which was given to the [[Naval Intelligence Division (UK)|Director of Naval Intelligence]], [[Hugh Sinclair]].<ref name="johnson44">Johnson, 1997, p. 44</ref> Sinclair merged staff from NID25 and MI1b into the new organisation, which initially consisted of around 25–30 officers and a similar number of clerical staff.<ref>Johnson, 1997, p. 45 and Kahn, 1991, p. 82; these sources give different numbers for the initial size of the GC&CS staff</ref> It was titled the "Government Code and Cypher School" (GC&CS), a cover-name which was chosen by Victor Forbes of the [[Foreign Office]].<ref>{{Cite book|last=Macksey|first=Kenneth|title=The Searchers: How Radio Interception Changed the Course of Both World Wars|year=2003| publisher=Cassell Military|isbn=0-304-36545-9|page=58}}</ref> [[Alastair Denniston]], who had been a member of NID25, was appointed as its operational head.<ref name="johnson44"/> It was initially under the control of the [[British Admiralty|Admiralty]] and located in Watergate House, Adelphi, London.<ref name="johnson44"/> Its public function was "to advise as to the security of codes and cyphers used by all Government departments and to assist in their provision", but also had a secret directive to "study the methods of cypher communications used by foreign powers".<ref>Smith, 2001, pp. 16–17</ref> GC&CS officially formed on 1 November 1919,<ref>Kahn, 1991, p. 82</ref> and produced its first decrypt prior to that date, on 19 October.<ref name="johnson44"/>

[[File:Allidina-Visram.jpg|thumbnail|right|Allidina Visram school in Mombasa, pictured above in 2006, was the location of the British "Kilindini" codebreaking outpost during World War II.]]

Before the Second World War, GC&CS was a relatively small department. By 1922, the main focus of GC&CS was on diplomatic traffic, with "no service traffic ever worth circulating"<ref name="and">{{cite journal |first=Alastair G. |last=Denniston |title=The Government Code and Cypher School Between the Wars |journal=Intelligence and National Security |volume=1 |issue=1 |pages=48–70 |year=1986 |doi=10.1080/02684528608431841 }}</ref> and so, at the initiative of Lord Curzon, it was transferred from the Admiralty to the [[Foreign Office]].<ref>Smith, 2001, pp. 20–21</ref> GC&CS came under the supervision of [[Hugh Sinclair]], who by 1923 was both the Chief of [[Secret Intelligence Service|SIS]] and Director of GC&CS.<ref name="johnson44"/> In 1925, both organisations were co-located on different floors of Broadway Buildings, opposite [[St. James's Park]].<ref name="johnson44"/> Messages decrypted by GC&CS were distributed in blue-jacketed files that became known as "BJs".<ref>Smith, 2001, pp. 18–19</ref> In the 1920s, GC&CS was successfully reading Soviet Union diplomatic cyphers. However, in May 1927, during a row over clandestine Soviet support for the [[1926 United Kingdom general strike|General Strike]] and the distribution of subversive propaganda, Prime Minister [[Stanley Baldwin]] made details from the decrypts public.{{sfn|Aldrich|2010|p= 18}}

===World War II===
During the Second World War, GC&CS was based largely at [[Bletchley Park]], in present-day [[Milton Keynes]], working on understanding the German [[Enigma machine]] and [[Lorenz cipher]]s.<ref>{{cite book |first=Paul |last=Gannon |title=Colossus: Bletchley Park's Greatest Secret |publisher=Atlantic Books |year=2006 |isbn=978-1-84354-331-2}}</ref> In 1940, GC&CS was working on the diplomatic codes and ciphers of 26 countries, tackling over 150 diplomatic cryptosystems.<ref>{{cite book |first=David |last=Alvarez |chapter=Most Helpful and Cooperative: GC&CS and the Development of American Diplomatic Cryptanalysis, 1941–1942 |title=Action This Day: Bletchley Park from the Breaking of the Enigma Code to the Birth of the Modern Computer |editor1-first=Michael |editor1-last=Smith |editor2-first=Ralph| editor2-last=Erskine |publisher=Bantam Press |year=2001 |isbn=978-0593049105}}</ref> Senior staff included [[Alastair Denniston]], [[Oliver Strachey]], [[Dilly Knox]], [[John Tiltman]], [[Edward Travis]], [[Ernst Fetterlein]], [[Josh Cooper (cryptographer)|Josh Cooper]], [[Donald Michie]], [[Alan Turing]], [[Gordon Welchman]], [[Joan Clarke]], [[Max Newman]], [[William Tutte]], [[I. J. Good|I. J. (Jack) Good]], [[Peter Calvocoressi]] and [[Hugh Foss]].<ref>{{Citation | editor-last = Erskine | editor-first = Ralph | editor2-last = Smith | editor2-first = Michael | editor2-link = Michael Smith (newspaper reporter) | title = The Bletchley Park Codebreakers | publisher = Biteback Publishing Ltd | year = 2011 | isbn = 978-1-84954-078-0}}</ref> The 1943 British–US Communication Intelligence Agreement, [[1943 BRUSA Agreement|BRUSA]], connected the signal intercept networks of the GC&CS and the US [[National Security Agency]] (NSA).<ref>{{Cite news |date=2016-02-08 |title=How the British and Americans started listening in |language=en-GB |work=BBC News |url=https://www.bbc.com/news/magazine-35491822 |access-date=2023-04-02 |archive-date=2 April 2023 |archive-url=https://web.archive.org/web/20230402082849/https://www.bbc.com/news/magazine-35491822 |url-status=live }}</ref><ref>{{Cite news |date=2021-03-05 |title=Diary reveals birth of secret UK-US spy pact that grew into Five Eyes |language=en-GB |work=BBC News |url=https://www.bbc.com/news/uk-56284453 |access-date=2023-04-02 |archive-date=2 April 2023 |archive-url=https://web.archive.org/web/20230402082850/https://www.bbc.com/news/uk-56284453 |url-status=live }}</ref> Equipment used to break enemy codes included the [[Colossus computer]].<ref>{{Citation |editor-last= Preneel |editor-first= Bart |title= Advances in Cryptology - EUROCRYPT 2000: International Conference on the Theory and Application of Cryptographic Techniques Bruges, Belgium May 14-18, 2000, Proceedings |publisher=  Springer |series= Lecture Notes in Computer Science |year= 2000 |volume= 1807 |isbn= 978-3540675174|contribution-url=https://www.iacr.org/archive/eurocrypt2000/1807/18070423-new.pdf |archive-url=https://web.archive.org/web/20081120221724/http://www.iacr.org/archive/eurocrypt2000/1807/18070423-new.pdf |archive-date=2008-11-20 |url-status=live |contribution=Colossus and the German Lorenz Cipher – Code Breaking in WW II |page=417 |doi=10.1007/3-540-45539-6_29 |doi-access= free }}</ref> Colossus consisted of ten networked computers.<ref>{{cite news|url=https://www.bbc.com/news/technology-67997406 |title=Unseen images of code breaking computer that helped win WW2|date= 17 January 2024|first= Shiona|last= McCallum|newspaper=BBC|access-date=21 January 2024}}</ref>

An outstation in the Far East, the [[Far East Combined Bureau]], was set up in Hong Kong in 1935 and moved to Singapore in 1939. Subsequently, with the Japanese advance down the Malay Peninsula, the Army and RAF codebreakers went to the [[Wireless Experimental Centre]] in Delhi, India. The Navy codebreakers in FECB went to [[Colombo]], Ceylon, then to [[Kilindini]], near [[Mombasa]], Kenya.<ref>{{cite web|url=http://www.coastweek.com/codes.htm|title=Mombasa was base for high-level UK espionage operation|publisher=Coastweek|access-date=25 February 2018|archive-date=15 May 2013|archive-url=https://web.archive.org/web/20130515123737/http://www.coastweek.com/codes.htm|url-status=usurped}}</ref>

===Post Second World War===
GC&CS was renamed the Government Communications Headquarters (GCHQ) in June 1946.<ref>{{Cite book|last= Smith|first=Michael|title=Station X|year=1998|publisher=Channel 4 books|isbn=0-330-41929-3|page= 176}}</ref>

The organisation was at first based in [[RAF Eastcote|Eastcote]] in northwest London, then in 1951<ref>{{cite web|url=http://www.gchq.gov.uk/about/moving5.html|title=History of GCHQ Cheltenham|work=GCHQ website 'About Us' pages|access-date=29 June 2006 |archive-url = https://web.archive.org/web/20061005175413/http://www.gchq.gov.uk/about/moving5.html <!-- Bot retrieved archive --> |archive-date = 5 October 2006}}</ref> moved to the outskirts of [[Cheltenham]], setting up two sites at [[Oakley, Gloucestershire|Oakley]] and [[Benhall, Cheltenham|Benhall]]. One of the major reasons for selecting Cheltenham was that the town had been the location of the headquarters of the [[United States Army Services of Supply]] for the European Theater during the War, which built up a telecommunications infrastructure in the region to carry out its logistics tasks.<ref>{{cite web |url=https://www.theregister.com/2013/05/24/geeks_guide_gchq/?page=1 |title=INSIDE GCHQ: Welcome to Cheltenham's cottage industry |last=Dormon |first=Bob |date=24 May 2013 |website=[[The Register]] |access-date=6 September 2016 |archive-date=6 September 2021 |archive-url=https://web.archive.org/web/20210906130613/https://www.theregister.com/2013/05/24/geeks_guide_gchq/?page=1 |url-status=live }}</ref>

Following the [[Second World War]], US and British intelligence have shared information as part of the [[UKUSA Agreement]]. The principal aspect of this is that GCHQ and its US equivalent, the National Security Agency (NSA), share technologies, infrastructure and information.<ref>{{cite book |title=Dirty Diplomacy |first=Craig |last=Murray |date=16 October 2007 |publisher=Scribner |page=332 |isbn=978-1416548010}}</ref><ref name="ferris"/>

GCHQ ran many [[signals intelligence]] (SIGINT) monitoring stations abroad. During the early [[Cold War]], the remnants of the [[British Empire]] provided a global network of ground stations which were a major contribution to the UKUSA Agreement; the US regarded [[RAF Little Sai Wan]] in [[Hong Kong]] as the most valuable of these. The monitoring stations were largely run by inexpensive [[Conscription in Great Britain#After 1945|National Service]] recruits, but when this ended in the early 1960s, the increased cost of civilian employees caused budgetary problems. In 1965 a Foreign Office review found that 11,500 staff were involved in SIGINT collection (8,000 GCHQ staff and 3,500 military personnel), exceeding the size of the [[Her Majesty's Diplomatic Service|Diplomatic Service]]. Reaction to the [[Suez War]] led to the eviction of GCHQ from several of its best foreign SIGINT collection sites, including the new [[Far East Combined Bureau|Perkar, Ceylon site]] and [[RAF Habbaniya]], Iraq. The staff largely moved to tented encampments on military bases in Cyprus, which later became the [[Sovereign Base Area]].<ref name="aldrich-2011" >{{cite book |pages=117–118, 153, 155, 160–162, 227–228, 475 |url=https://books.google.com/books?id=l9i5bt1-7HYC |last=Aldrich |first=Richard J. |year=2011 |title=GCHQ |location=London |publisher=Harper Press |isbn=978-0-007312-665 |access-date=21 March 2023 |archive-date=4 April 2023 |archive-url=https://web.archive.org/web/20230404131620/https://books.google.com/books?id=l9i5bt1-7HYC |url-status=live }}</ref>

During the [[Cuban Missile Crisis]], [[GCHQ Scarborough]] intercepted radio communications from Soviet ships reporting their positions and used that to establish where they were heading. A copy of the report was sent directly to the White House Situation Room, providing initial indications of Soviet intentions with regards the US naval blockade of Cuba.<ref name=":0">{{Cite news |last=Corera |first=Gordon |date=2019-10-21 |title=Scarborough's Cuban missile crisis role revealed |language=en-GB |url=https://www.bbc.com/news/uk-50098955 |access-date=2019-10-21 |archive-date=5 December 2019 |archive-url=https://web.archive.org/web/20191205204023/https://www.bbc.com/news/uk-50098955 |url-status=live }}</ref>

[[Duncan Campbell (journalist, born 1952)|Duncan Campbell]] and [[Mark Hosenball]] revealed the existence of GCHQ in 1976 in an article for ''[[Time Out (magazine)|Time Out]]''; as a result, Hosenball was deported from the UK.<ref>{{cite magazine |magazine=Time Out |title=The Eavesdroppers |author1=Duncan Campbell |author2=Mark Hosenball |url=http://www.duncancampbell.org/PDF/1976-may-time-out-the-eavesdroppers.pdf |archive-url=https://web.archive.org/web/20131101152620/http://www.duncancampbell.org/PDF/1976-may-time-out-the-eavesdroppers.pdf |archive-date=2013-11-01 |url-status=live |date=21 May 1976 |access-date=1 March 2016}}</ref><ref>Court ruling, "[http://www.uniset.ca/other/css/hosenball.html R v Secretary of State for the Home Department, ex parte Hosenball] {{Webarchive|url=https://web.archive.org/web/20160521131820/http://www.uniset.ca/other/css/hosenball.html |date=21 May 2016 }}", [1977] 1 W.L.R. 766; [1977] 3 All E.R. 452.  Lord Denning presiding judge, 29 March 1977.</ref> GCHQ had a very low profile in the media until 1983 when the trial of [[Geoffrey Prime]], a [[KGB]] mole within it, created considerable media interest.{{sfn|Aldrich|2010|p= 382}}

====Trade union disputes====
{{Main|Council of Civil Service Unions v Minister for the Civil Service|GCHQ trade union ban}}
[[File:NUCPS banner.jpg|thumb|right|[[NUCPS]] banner on march in [[Cheltenham]] 1992]]
In 1984, GCHQ was the centre of a political row when, in the wake of strikes which affected Sigint collection, the [[Conservative Party (UK)|Conservative]] government of [[Margaret Thatcher]] prohibited its employees from belonging to a trade union, asserting that membership of a union was in conflict with [[national security]].<ref name="ferris"/> The government offered £1,000 to each employee who agreed to give up their right to union membership. Following the breakdown of talks and the failure to negotiate a no-strike agreement, a number of mass national one-day strikes were held to protest against this decision, believed by some to be the first step to wider bans on trade unions. Appeals to British courts and the [[European Commission of Human Rights]]<ref>{{cite web |url=http://cmiskp.echr.coe.int/tkp197/view.asp?action=html&documentId=664551&portal=hbkm&source=externalbydocnumber&table=F69A27FD8FB86142BF01C1166DEA398649 |title=EComHR Inadmissibility decision of EComHR on application no. 11603/85 |year=1987 |access-date=15 November 2010 |archive-date=4 June 2012 |archive-url=https://web.archive.org/web/20120604022433/http://cmiskp.echr.coe.int/tkp197/view.asp?action=html&documentId=664551&portal=hbkm&source=externalbydocnumber&table=F69A27FD8FB86142BF01C1166DEA398649 |url-status=live }}</ref> were unsuccessful. An appeal to the [[International Labour Organization]] resulted in a decision that the government's actions were in violation of [[Freedom of Association and Protection of the Right to Organise Convention]].<ref>{{cite web |url=http://cmiskp.echr.coe.int/tkp197/view.asp?action=html&documentId=664551&portal=hbkm&source=externalbydocnumber&table=F69A27FD8FB86142BF01C1166DEA398649 |title=EComHR Inadmissibility decision of EComHR on application no. 11603/85 – The Facts |access-date=15 November 2010 |archive-date=4 June 2012 |archive-url=https://web.archive.org/web/20120604022433/http://cmiskp.echr.coe.int/tkp197/view.asp?action=html&documentId=664551&portal=hbkm&source=externalbydocnumber&table=F69A27FD8FB86142BF01C1166DEA398649 |url-status=live }} para. IV</ref>

A no-strike agreement was eventually negotiated and the ban lifted by the incoming [[Labour Party (UK)|Labour]] government in 1997, with the Government Communications Group of the [[Public and Commercial Services Union]] (PCS) being formed to represent interested employees at all grades.<ref>{{cite web|url=http://www.gchq.gov.uk/recruitment/union.html |title=Union representation |work=GCHQ website |access-date=12 April 2006 |url-status=dead |archive-url=https://web.archive.org/web/20060509054114/http://www.gchq.gov.uk/recruitment/union.html |archive-date=9 May 2006 }}</ref><ref name="ferris"/> In 2000, a group of 14 former GCHQ employees, who had been dismissed after refusing to give up their union membership, were offered re-employment, which three of them accepted.<ref>{{cite news|url=http://news.bbc.co.uk/1/hi/uk/627574.stm|title=Sacked GCHQ workers win compensation|work=BBC News|date=1 February 2000|access-date=12 April 2006|archive-date=1 September 2017|archive-url=https://web.archive.org/web/20170901074152/http://news.bbc.co.uk/1/hi/uk/627574.stm|url-status=live}}</ref>

The legal case ''[[Council of Civil Service Unions v Minister for the Civil Service]]'' is significant beyond the dispute, and even beyond trade union law, in that it held for the first time that the [[royal prerogative]] is generally subject to [[judicial review]], although the House of Lords ruled in favour of the Crown in this instance.<ref>{{cite book |first=Ewan |last=McGaughey |title=A Casebook on Labour Law |chapter-url={{GBurl|Wnx7DwAAQBAJ|page=323}} |publisher=Hart |date=2019 |chapter=8: Trade Unions |isbn=978-1-84946-931-9|page=360}}</ref>

===Post Cold War===

====1990s: Post-Cold War restructuring====
The [[Intelligence Services Act 1994]] formalised the activities of the intelligence agencies for the first time, defining their purpose, and the British Parliament's [[Intelligence and Security Committee]] was given a remit to examine the expenditure, administration and policy of the three intelligence agencies.<ref name="ISC">{{cite web|title=ISC – About|url=http://isc.independent.gov.uk/|publisher=Intelligence and Security Committee of Parliament|access-date=1 December 2013|archive-date=25 December 2010|archive-url=https://web.archive.org/web/20101225070246/http://isc.independent.gov.uk/|url-status=live}}</ref> The objectives of GCHQ were defined as working as "in the interests of national security, with particular reference to the defence and foreign policies of His Majesty's government; in the interests of the economic wellbeing of the United Kingdom; and in support of the prevention and the detection of serious crime".<ref name="InTel94">{{cite web|title=Intelligence Services Act 1994|url=http://www.legislation.gov.uk/ukpga/1994/13/section/3|publisher=The National Archives|access-date=1 December 2013|archive-date=2 December 2013|archive-url=https://web.archive.org/web/20131202105208/http://www.legislation.gov.uk/ukpga/1994/13/section/3|url-status=live}}</ref> During the introduction of the Intelligence Agency Act in late 1993, the former Prime Minister [[Jim Callaghan]] had described GCHQ as a "full-blown bureaucracy", adding that future bodies created to provide oversight of the intelligence agencies should "investigate whether all the functions that GCHQ carries out today are still necessary."<ref name="Dec93Hans">{{cite web|title=Hansard: December 1993 Intelligence Services Bill|work=[[Hansard|Parliamentary Debates (Hansard)]]|date=9 December 1993|url=https://api.parliament.uk/historic-hansard/lords/1993/dec/09/intelligence-services-bill-hl|access-date=11 March 2014|archive-date=19 March 2014|archive-url=https://web.archive.org/web/20140319035248/http://hansard.millbanksystems.com/lords/1993/dec/09/intelligence-services-bill-hl|url-status=live}}</ref>

In late 1993 civil servant [[Michael Quinlan (civil servant)|Michael Quinlan]] advised a deep review of the work of GCHQ following the conclusion of his "Review of Intelligence Requirements and Resources", which had imposed a 3% cut on the agency.{{sfn|Aldrich|2010|p=493}} The [[Chief Secretary to the Treasury]], [[Jonathan Aitken]], subsequently held face to face discussions with the intelligence agency directors to assess further savings in the wake of Quinlan's review. Aldrich (2010) suggests that Sir [[John Adye]], the then Director of GCHQ performed badly in meetings with Aitken, leading Aitken to conclude that GCHQ was "suffering from out-of-date methods of management and out-of-date methods for assessing priorities".{{sfn|Aldrich|2010|p=494}} GCHQ's budget was £850&nbsp;million in 1993, (£{{Formatprice|{{Inflation|UK|850000000|1993|{{inflation-year|UK}}|r=0}}}} as of {{inflation-year|UK}}){{Inflation-fn|UK}} compared to £125&nbsp;million for the Security Service and SIS (MI5 and MI6). In December 1994 the businessman Roger Hurn was commissioned to begin a review of GCHQ, which was concluded in March 1995.<ref name="Aldrich, 2010, 495" >{{harvnb|Aldrich|2010|p=495}}</ref> Hurn's report recommended a cut of £100&nbsp; million in GCHQ's budget; such a large reduction had not been suffered by any British intelligence agency since the end of World War II.<ref name="Aldrich, 2010, 495"/> The J Division of GCHQ, which had collected SIGINT on Russia, disappeared as a result of the cuts.<ref name="Aldrich, 2010, 495"/> The cuts had been mostly reversed by 2000 in the wake of threats from [[violent non-state actor]]s, and risks from increased terrorism, organised crime and illegal access to nuclear, chemical and biological weapons.<ref name="Aldrich, 2010, 505" >{{harvnb|Aldrich|2010|p=505}}</ref>

[[David Omand]] became the Director of GCHQ in 1996, and greatly restructured the agency in the face of new and changing targets and rapid technological change.<ref name="Aldrich, 2010, 496" >{{harvnb|Aldrich|2010|p=496}}</ref> Omand introduced the concept of "Sinews" (or "SIGINT New Systems") which allowed more flexible working methods, avoiding overlaps in work by creating fourteen domains, each with a well-defined working scope.<ref name="Aldrich, 2010, 496"/> The tenure of Omand also saw the construction of a modern new headquarters, intended to consolidate the two old sites at Oakley and Benhall into a single, more open-plan work environment.<ref name="Aldrich, 2010, 496"/> Located on a 176-acre site in Benhall, it would be the largest building constructed for secret intelligence operations outside the United States.{{sfn|Aldrich|2010|p=9}}<ref name="ferris"/>

Operations at GCHQ's [[Chung Hom Kok]] listening station in Hong Kong ended in 1994.<ref name="Aldrich, 2010, 475" >{{harvnb|Aldrich|2010|p=475}}</ref> GCHQ's Hong Kong operations were extremely important to their relationship with the NSA, who contributed investment and equipment to the station. In anticipation of the [[Transfer of sovereignty over Hong Kong|transfer of Hong Kong to the Chinese government]] in 1997, the Hong Kong stations operations were moved to [[Australian Defence Satellite Communications Station]] in [[Geraldton]] in [[Western Australia]].<ref name="West2012">{{cite book|author=Nigel West|title=Historical Dictionary of Signals Intelligence|url=https://books.google.com/books?id=maJbZGwK4BAC&pg=PR27 |date=31 August 2012|publisher=Scarecrow Press|isbn=978-0-8108-7391-9|pages=27–}}</ref>

Operations that used GCHQ's intelligence-gathering capabilities in the 1990s included the monitoring of communications of Iraqi soldiers in the [[Gulf War]], of [[dissident republican]] terrorists and the [[Real IRA]], of the various factions involved in the [[Yugoslav Wars]], and of the criminal [[Kenneth Noye]].<ref name="Aldrich, 2010, 505"/><ref name="West2012"/><ref name="Aldrich, 2010, 473" >{{harvnb|Aldrich|2010|p=473}}</ref> In the mid-1990s GCHQ began to assist in the investigation of [[cybercrime]].<ref name="Aldrich, 2010, 489" >{{harvnb|Aldrich|2010|p=489}}</ref>

====2000s: Coping with the Internet====
{{See also|Global surveillance|Global surveillance disclosures (2013–present)}}
At the end of 2003, GCHQ moved in to its new building. Built on a circular plan around a large central courtyard, it quickly became known as [[the Doughnut]]. At the time, it was one of the largest public-sector building projects in Europe, with an estimated cost of £337 million. The new building, which was designed by [[Gensler]] and constructed by [[Carillion]], became the base for all of GCHQ's [[Cheltenham]] operations.<ref>{{cite news |url=http://news.bbc.co.uk/1/hi/business/931773.stm |title=Carillion set for growth |work=BBC News |date=19 September 2000 |access-date=22 December 2007 |archive-date=27 February 2009 |archive-url=https://web.archive.org/web/20090227151049/http://news.bbc.co.uk/1/hi/business/931773.stm |url-status=live }}</ref>

The public spotlight fell on GCHQ in late 2003 and early 2004 following the sacking of [[Katharine Gun]] after she leaked to ''[[The Observer]]'' a confidential email from agents at the United States' [[National Security Agency]] addressed to GCHQ officers about the wiretapping of UN delegates in the run-up to the [[2003 Iraq war]].<ref>Aldrich, 2010, p. 521</ref>

GCHQ gains its intelligence by monitoring a wide variety of communications and other electronic signals. For this, a number of stations have been established in the UK and overseas. The listening stations are at Cheltenham itself, [[GCHQ Bude|Bude]], [[GCHQ Scarborough|Scarborough]], [[Ascension Island]], and with the United States at [[RAF Menwith Hill]].<ref>{{cite journal |last=Campbell |first=Duncan |author-link=Duncan Campbell (journalist, born 1952) |title=Phone tappers and the state |journal=New Statesman |year=1981 |page=54}}</ref> [[Ayios Nikolaos Station]] in Cyprus is run by the [[British Army]] for GCHQ.<ref>Aldrich, 2010, p. 471</ref>

In March 2010, GCHQ was criticised by the [[Intelligence and Security Committee]] for problems with its IT security practices and failing to meet its targets for work targeted against cyber attacks.<ref>{{cite web |url= http://www.computerworlduk.com/management/government-law/public-sector/news/index.cfm?newsid=19344 |title= 'Cavalier' GCHQ online spy centre loses 35 laptops |publisher= [[Computerworld UK]] |date= 12 March 2010 |access-date= 12 March 2010 |archive-date= 29 July 2012 |archive-url= https://archive.today/20120729004038/http://www.computerworlduk.com/management/government-law/public-sector/news/index.cfm?newsid=19344 |url-status= live }}</ref>

As revealed by [[Edward Snowden]] in ''[[The Guardian]]'', GCHQ spied on foreign politicians visiting the [[2009 G-20 London Summit]] by eavesdropping phonecalls and emails and monitoring their computers, and in some cases even ongoing after the summit via [[keystroke logging]] that had been undertaken during the summit.<ref>''The Guardian'': [https://www.theguardian.com/uk/2013/jun/16/gchq-intercepted-communications-g20-summits GCHQ intercepted foreign politicians' communications at G20 summits] {{Webarchive|url=https://web.archive.org/web/20131018004108/http://www.theguardian.com/uk/2013/jun/16/gchq-intercepted-communications-g20-summits |date=18 October 2013 }}, 16 June 2013</ref>

According to Edward Snowden, at that time GCHQ had two principal umbrella programs for collecting communications:
* "[[Mastering the Internet]]" (MTI) for Internet traffic, which is extracted from fibre-optic cables and can be searched by using the [[Tempora]] computer system.
* "[[Global Telecoms Exploitation]]" (GTE) for telephone traffic.<ref name=bump>{{cite web |url=http://www.theatlanticwire.com/national/2013/06/uk-tempora-program/66490/ |author=Philip Bump |title=The UK Tempora Program Captures Vast Amounts of Data – and Shares with NSA |publisher=The Atlantic Wire |date=21 June 2013 |access-date=23 June 2013 |archive-date=5 November 2013 |archive-url=https://web.archive.org/web/20131105105045/http://www.theatlanticwire.com/national/2013/06/uk-tempora-program/66490/ |url-status=dead }}</ref>

GCHQ has also had access to the US internet monitoring programme [[PRISM]] from at least as far back as June 2010.<ref>{{cite web|title=Statement on GCHQ's Alleged Interception of Communications under the US PRISM Programme|url=https://isc.independent.gov.uk/wp-content/uploads/2021/01/20130717_ISC_statement_GCHQ.pdf|url-status=live|publisher=Intelligence and Security Committee of Parliament|access-date=19 April 2023|date=17 July 2013|archive-date=19 April 2023|archive-url=https://web.archive.org/web/20230419142038/https://isc.independent.gov.uk/wp-content/uploads/2021/01/20130717_ISC_statement_GCHQ.pdf}}</ref> PRISM is said to give the [[National Security Agency]] and FBI easy access to the systems of nine of the world's top internet companies, including Google, Facebook, Microsoft, Apple, Yahoo, and Skype.<ref>{{cite web |url= https://www.bbc.co.uk/news/world-22860964 |title= Scale and significance of NSA snooping claims |publisher= BBC |date= 11 June 2013 |access-date= 20 June 2018 |archive-date= 17 June 2015 |archive-url= https://web.archive.org/web/20150617020056/http://www.bbc.co.uk/news/world-22860964 |url-status= live }}</ref>

From 2013, GCHQ realised that public attitudes to Sigint had changed and its former unquestioned secrecy was no longer appropriate or acceptable. The growing use of the Internet, together with its inherent insecurities, meant that the communications traffic of private citizens were becoming inextricably mixed with those of their targets and openness in the handling of this issue was becoming essential to their credibility as an organisation. The Internet had become a "cyber commons", with its dominance creating a "second age of Sigint". GCHQ transformed itself accordingly, including greatly expanded Public Relations and Legal departments, and adopting public education in cyber security as an important part of its remit.<ref>Ferris (2020), Chapters 14 and 15.</ref>

==== 2010s: Disinformation, discord and division ====
In February 2014, ''The Guardian'', based on documents provided by Snowden, revealed that GCHQ had indiscriminately collected 1.8&nbsp;million private Yahoo webcam images from users across the world.<ref>{{cite news|url=https://www.theguardian.com/world/2014/feb/27/gchq-nsa-webcam-images-internet-yahoo|title=Optic Nerve: millions of Yahoo webcam images intercepted by GCHQ|date=28 February 2014|access-date=2 March 2014|newspaper=The Guardian|last1=Ackerman|first1=Spencer|last2=Ball|first2=James|archive-date=23 September 2016|archive-url=https://web.archive.org/web/20160923234026/https://www.theguardian.com/world/2014/feb/27/gchq-nsa-webcam-images-internet-yahoo|url-status=live}}</ref> In the same month NBC and [[The Intercept]], based on documents released by Snowden, revealed the [[Joint Threat Research Intelligence Group]] and the Computer Network Exploitation units within GCHQ. Their mission was cyber operations based on "dirty tricks" to shut down enemy communications, discredit, and plant misinformation on enemies.<ref name=NBCFeb14>{{cite web|title=Snowden Docs: British Spies Used Sex and 'Dirty Tricks'|url=https://www.nbcnews.com/news/investigations/snowden-docs-british-spies-used-sex-dirty-tricks-n23091|work=[[NBC News]]|access-date=7 February 2014|date=7 February 2014|archive-date=7 February 2021|archive-url=https://web.archive.org/web/20210207161642/https://www.nbcnews.com/news/investigations/snowden-docs-british-spies-used-sex-dirty-tricks-n23091|url-status=live}}</ref> These operations were 5% of all GCHQ operations according to a conference slideshow presented by the GCHQ.<ref name="nbcslideshow22">{{cite web|title=The Snowden Files: British Spies Used Sex and 'Dirty' Tricks|url=http://msnbcmedia.msn.com/i/msnbc/sections/news/snowden_cyber_offensive2_nbc_document.pdf|website=NBC News Investigations|publisher=NBC|access-date=5 April 2015|archive-url=https://web.archive.org/web/20150112222153/http://msnbcmedia.msn.com/i/msnbc/sections/news/snowden_cyber_offensive2_nbc_document.pdf|archive-date=12 January 2015|url-status=dead}}</ref>

Soon after becoming Director of GCHQ in 2014, [[Robert Hannigan]] wrote an article in the ''[[Financial Times]]'' on the topic of [[internet surveillance]], stating that "however much [large US technology companies] may dislike it, they have become the command and control networks of choice for terrorists and criminals" and that GCHQ and its sister agencies "cannot tackle these challenges at scale without greater support from the private sector", arguing that most internet users "would be comfortable with a better and more sustainable relationship between the [intelligence] agencies and the tech companies". Since the [[2013 global surveillance disclosures]], large US technology companies have improved security and become less co-operative with foreign intelligence agencies, including those of the UK, generally requiring a US court order before disclosing data.<ref name="ft-20141103rh">{{cite news |url=http://www.ft.com/cms/s/2/c89b6c58-6342-11e4-8a63-00144feabdc0.html |archive-url=https://ghostarchive.org/archive/20221210/http://www.ft.com/cms/s/2/c89b6c58-6342-11e4-8a63-00144feabdc0.html |archive-date=10 December 2022 |url-access=subscription |title=The web is a terrorist's command-and-control network of choice |author=Robert Hannigan |newspaper=Financial Times |date=3 November 2014 |access-date=3 November 2014}}</ref><ref name="ft-20141103">{{cite news |url=http://www.ft.com/cms/s/2/4a35c0b2-636e-11e4-9a79-00144feabdc0.html |archive-url=https://ghostarchive.org/archive/20221210/http://www.ft.com/cms/s/2/4a35c0b2-636e-11e4-9a79-00144feabdc0.html |archive-date=10 December 2022 |url-access=subscription |url-status=live |title=Tech groups aid terror, says UK spy chief |author=Sam Jones and Murad Ahmed |newspaper=Financial Times |date=3 November 2014 |access-date=3 November 2014}}</ref> However the head of the UK technology industry group [[techUK]] rejected these claims, stating that they understood the issues but that disclosure obligations "must be based upon a clear and transparent legal framework and effective oversight rather than, as suggested, a deal between the industry and government".<ref name="telegraph-20141104">{{cite news |url=https://www.telegraph.co.uk/technology/11208999/Tech-giants-reject-GCHQ-boss-Robert-Hannigans-call-for-deal-with-government.html |archive-url=https://ghostarchive.org/archive/20220112/https://www.telegraph.co.uk/technology/11208999/Tech-giants-reject-GCHQ-boss-Robert-Hannigans-call-for-deal-with-government.html |archive-date=12 January 2022 |url-access=subscription |url-status=live |title=Tech giants reject GCHQ boss Robert Hannigan's call for deal with government |author=David Barrett |newspaper=The Daily Telegraph |date=4 November 2014 |access-date=5 November 2014}}{{cbignore}}</ref>

In 2015, documents obtained by ''[[The Intercept]]'' from US [[National Security Agency]] whistleblower [[Edward Snowden]] revealed that GCHQ had carried out a mass-surveillance operation, codenamed [[Karma Police (surveillance program)|KARMA POLICE]], since about 2008.<ref name="Karma">Ryan Gallager, [https://theintercept.com/2015/09/25/gchq-radio-porn-spies-track-web-users-online-identities/ Profiled: From Radio to Porn, British Spies Track Web Users' Online Identities] {{Webarchive|url=https://web.archive.org/web/20210910193008/https://theintercept.com/2015/09/25/gchq-radio-porn-spies-track-web-users-online-identities/ |date=10 September 2021 }}, ''The Intercept'' (25 September 2015).</ref> The operation swept up the [[IP address]] of Internet users visiting websites, and was established with no public scrutiny or oversight. KARMA POLICE is a powerful spying tool in conjunction with other GCHQ programs because IP addresses could be cross-referenced with other data.<ref name="Karma"/> The goal of the program, according to the documents, was "either (a) a web browsing profile for every visible user on the internet, or (b) a user profile for every visible website on the internet."<ref name="Karma"/>

In 2015, GCHQ admitted for the first time in court that it conducts computer hacking.<ref>Croft, Jane (1 December 2015) [http://www.ft.com/cms/s/0/7e9d93b2-9832-11e5-9228-87e603d47bdc.html UK spy agency GCHQ admits it carries out computer hacking] {{Webarchive|url=https://web.archive.org/web/20151203223413/http://www.ft.com/cms/s/0/7e9d93b2-9832-11e5-9228-87e603d47bdc.html |date=3 December 2015 }}. ''Financial Times''</ref>

In 2017, US Press Secretary [[Sean Spicer]] made allegations that GCHQ had conducted surveillance on US President [[Donald Trump]]. These unfounded claims were based on statements made during an opinion piece in a FOX media segment.<ref>Farrell, Henry (16 March 2017) [https://www.washingtonpost.com/news/monkey-cage/wp/2017/03/16/sean-spicer-just-suggested-that-obama-used-british-intelligence-to-spy-on-trump-not-so-much/ Sean Spicer just suggested that Obama used British intelligence to spy on Trump. Not so much] {{Webarchive|url=https://web.archive.org/web/20170317020548/https://www.washingtonpost.com/news/monkey-cage/wp/2017/03/16/sean-spicer-just-suggested-that-obama-used-british-intelligence-to-spy-on-trump-not-so-much/ |date=17 March 2017 }}. ''The Washington Post''</ref><ref>Blake, Aaron (16 March 2017) [https://www.washingtonpost.com/news/the-fix/wp/2017/03/16/sean-spicers-angry-lonely-defense-of-trumps-wiretapping-claim-annotated/ Sean Spicer's angry, lonely defense of Trump's wiretapping claim, annotated] {{Webarchive|url=https://web.archive.org/web/20170317053939/https://www.washingtonpost.com/news/the-fix/wp/2017/03/16/sean-spicers-angry-lonely-defense-of-trumps-wiretapping-claim-annotated/ |date=17 March 2017 }}. ''The Washington Post''</ref> The US government formally apologised for the unfounded allegations and promised they would not be repeated.<ref>{{cite news|title=US makes formal apology to Britain after White House accuses GCHQ of wiretapping Trump Tower|url=https://www.telegraph.co.uk/news/2017/03/17/us-makes-formal-apology-britain-white-house-accuses-gchq-wiretapping/|access-date=17 March 2017|work=The Telegraph|date=17 March 2017|archive-date=22 March 2017|archive-url=https://web.archive.org/web/20170322064105/https://www.telegraph.co.uk/news/2017/03/17/us-makes-formal-apology-britain-white-house-accuses-gchq-wiretapping/|url-status=live}}</ref><ref>{{cite news|title=White House apologizes to British government over spying claims|url=https://edition.cnn.com/2017/03/17/politics/gchq-trump-wiretap-denial/|access-date=17 March 2017|publisher=CNN|date=17 December 2017|archive-date=18 March 2017|archive-url=https://web.archive.org/web/20170318003415/http://edition.cnn.com/2017/03/17/politics/gchq-trump-wiretap-denial/|url-status=live}}</ref><ref>{{cite news |url=https://www.theguardian.com/us-news/2017/mar/16/gchq-denies-wiretap-claim-trump-obama |title=GCHQ dismisses 'utterly ridiculous' claim it helped wiretap Trump &#124; US news |newspaper=The Guardian |access-date=13 April 2017 |date=17 March 2017 |archive-date=21 April 2019 |archive-url=https://web.archive.org/web/20190421154146/https://www.theguardian.com/us-news/2017/mar/16/gchq-denies-wiretap-claim-trump-obama |url-status=live }}</ref>

British intelligence did gather information relating to Russian [[Links between Trump associates and Russian officials and spies|contacts made by Trump's campaign team]] in the run-up to his election, which were passed on to US intelligence agencies.<ref>{{cite news |url=https://www.theguardian.com/uk-news/2017/apr/13/british-spies-first-to-spot-trump-team-links-russia |title=British spies were first to spot Trump team's links with Russia |newspaper=The Guardian |access-date=13 April 2017 |date=13 April 2017 |last1=Harding |first1=Luke |last2=Kirchgaessner |first2=Stephanie |last3=Hopkins |first3=Nick |archive-date=13 April 2017 |archive-url=https://web.archive.org/web/20170413135157/https://www.theguardian.com/uk-news/2017/apr/13/british-spies-first-to-spot-trump-team-links-russia |url-status=live }}</ref><ref>{{cite news|title=British intelligence passed Trump associates' communications with Russians on to US counterparts|url=https://edition.cnn.com/2017/04/13/politics/trump-russia-british-intelligence/index.html?sr=twpol041317trump-russia-british-intelligence0910PMVODtopLink&linkId=36496320|access-date=14 April 2017|publisher=CNN|date=14 April 2017|archive-date=15 April 2017|archive-url=https://web.archive.org/web/20170415200602/http://edition.cnn.com/2017/04/13/politics/trump-russia-british-intelligence/index.html?sr=twpol041317trump-russia-british-intelligence0910PMVODtopLink&linkId=36496320|url-status=live}}</ref>

On 31 October 2018, GCHQ joined [[Instagram]].<ref>{{Cite web|url=https://www.instagram.com/gchq/|title=GCHQ (@gchq) • Instagram photos and videos|website=www.instagram.com|language=en|access-date=1 November 2018|archive-date=14 May 2020|archive-url=https://web.archive.org/web/20200514145303/https://www.instagram.com/gchq/|url-status=live}}</ref><ref>{{Cite web|url=https://www.theguardian.com/uk-news/2018/oct/31/gchq-uses-instagram-to-open-up-secret-world-of-espionage-to-public|title=GCHQ uses Instagram to 'open up world of espionage' to public|last=Weaver|first=Matthew|date=31 October 2018|website=The Guardian|language=en|access-date=1 November 2018|archive-date=31 October 2018|archive-url=https://web.archive.org/web/20181031234851/https://www.theguardian.com/uk-news/2018/oct/31/gchq-uses-instagram-to-open-up-secret-world-of-espionage-to-public|url-status=live}}</ref>