Editing Vanguard-class submarine (section)

==Development==
===Trident programme===
{{Main|Trident nuclear programme}}
Beginning in the late 1960s, the United Kingdom operated four {{sclass|Resolution|submarine|1}}s, each armed with sixteen US-built [[UGM-27 Polaris|UGM-27 Polaris missiles]]. The Polaris missile was supplied to Britain following the terms of the 1963 [[Polaris Sales Agreement]]. This nuclear deterrent system was known as the [[UK Polaris programme]]. In the early 1980s the British government began studies examining options for replacing the ''Resolution''-class submarines and their Polaris missiles, both of which would be approaching the end of their service lives within little over a decade.<ref name="1980DefenceCouncil">{{cite journal|last1=PYM|first1=Francis|title=The Future United Kingdom Strategic Nuclear Deterrent Force|journal=Ministry of Defence|date=July 1980|url=http://fc95d419f4478b3b6e5f-3f71d0fe2b653c4f00f32175760e96e7.r87.cf1.rackcdn.com/6AC6FE79AE5E485DB3A2B579B6AE0654.pdf|access-date=1 December 2016}}</ref> On 24 January 1980, the House of Commons backed government policy, by 308 votes to 52, to retain an independent nuclear deterrent. Options that were examined included:<ref name="1980DefenceCouncil"/>
*A British designed and built ballistic missile; Although Britain had had no capability in this field since the 1960s, it was considered "not to be impossible". However, it would be very expensive, would be full of uncertainty and would not be available within the required time period. Thus the option was considered "unattractive".
*Retain Polaris, but fitted on a new submarine class; This option would have a cheaper "initial capital cost", but would lack in terms of required capability and reliability. Also, it was concluded that any initial capital savings would have been lost beyond the 1990s, due to the high cost of sustaining a small stockpile of bespoke missiles kept only in British service.

A European solution and the US [[UGM-73 Poseidon]] were also briefly considered, but ultimately rejected, primarily on capability, cost and uncertainty grounds.<ref name="1980DefenceCouncil"/> The clear favourite was the [[UGM-96 Trident I]], which as well as being a cost-effective solution – given the US would also operate the missile in vast numbers – also delivered the overall best long-term capability insurances against Soviet advancements in [[ballistic missile defence]].<ref name="1980DefenceCouncil"/> Subsequently, on 10 July 1980, the then Prime Minister [[Margaret Thatcher]] wrote to US President [[Jimmy Carter]] requesting the purchase of Trident I missiles on a similar basis as the 1963 Polaris Sales Agreement. However, following the acceleration of the US [[UGM-133 Trident II]] missiles, Thatcher wrote to US President [[Ronald Reagan]] in 1982 requesting the United Kingdom be allowed to procure the improved system instead. An agreement was made in March 1982 between the two countries,<ref>[http://www.reagan.utexas.edu/archives/speeches/1982/31182b.htm Letter to Prime Minister Margaret Thatcher of the United Kingdom Confirming the Sale of the Trident II Missile System to the Her Country] {{Webarchive|url=https://web.archive.org/web/20100913055759/http://www.reagan.utexas.edu/archives/speeches/1982/31182b.htm |date=13 September 2010 }} 11 March 1982</ref> and under the agreement, Britain made a 5% research and development contribution.<ref name=NAO-1987>{{cite book|title=Ministry of Defence and Property Services Agency: Control and Management of the Trident Programme|publisher=[[National Audit Office (United Kingdom)|National Audit Office]]|date=29 June 1987|pages=Part 4|isbn=0-10-202788-9|no-pp=true}}</ref>

===Design and construction===
[[File:BAE Systems from Walney.jpg|thumb|left|The {{convert|25000|m2|abbr=on}} [[Devonshire Dock Hall]] indoor shipbuilding complex]]
The ''Vanguard'' class were designed in the early 1980s by the Ministry of Defence, acting in one of its last Royal Navy warship design authority roles. The guidance drawings were then supplied for detailed design development by [[Vickers Shipbuilding and Engineering]] (VSEL) based at [[Barrow-in-Furness]], now [[BAE Systems Maritime – Submarines]]. They were designed from the outset as nuclear-powered ballistic missile submarines, able to accommodate the UGM-133 Trident II missiles. As such, the missile compartment is based on the same system used on the American {{sclass|Ohio|submarine|4}}, which is also equipped with the UGM-133 Trident II. This requirement led to the ''Vanguard''-class design being significantly larger than the previous Polaris-equipped ''Resolution'' class, and at nearly 16,000 tonnes they are the largest submarines ever built for the Royal Navy.

Due to the large size of the ''Vanguard''-class, the [[Devonshire Dock Hall]] in Barrow-in-Furness was built between 1982 and 1986 specifically for the construction of the boats.<ref name="DDH">{{cite news |date=2 September 2011 |title=In pictures: Submarine 'shed' in Cumbria marks 25th year |work=BBC News |url=https://www.bbc.co.uk/news/uk-england-cumbria-14762995 |access-date=1 December 2016}}</ref>

Beginning in 1985, both [[HMNB Clyde]] and the [[RNAD Coulport|Royal Naval Armaments Depot Coulport]] at Faslane underwent extensive redevelopment in preparation for the ''Vanguard'' class submarines and Trident II missiles. [[Rosyth Dockyard|Rosyth dockyard]] also underwent significant redevelopment. The work included enhanced "handling, storage, armament processing, berthing, docking, engineering, training and refitting facilities" at an estimates cost of £550 million.<ref>{{cite web|title=Trident|url=https://api.parliament.uk/historic-hansard/written-answers/1985/jan/15/trident-1|publisher=Hansard, 15 January 1985|work=[[Hansard|Parliamentary Debates (Hansard)]]|date=15 January 1985|access-date=1 December 2016}}</ref>

Prime Minister Thatcher laid the keel of the first boat, HMS ''Vanguard'', on 3 September 1986 at the Devonshire Dock Hall.<ref>{{cite web |url= http://www.astuteclass.com/2011/09/ddh-celebrates-25th-birthday/ |title=DDH celebrates 25th birthday &#124; Astute Class Submarine – BAE Systems Maritime – Submarines |work=astuteclass.com |year=2012 |access-date=27 August 2012}}</ref> ''Vanguard'' was [[Ship naming and launching|launched]] in 1992 and [[Ship commissioning|commissioned]] in 1993. The year 1992 saw a debate over whether the fourth vessel, ''Vengeance'', should be cancelled; however, the Ministry of Defence ultimately ordered it in July 1992<ref>{{cite news |date=1992-07-08 |title=Trident order raises arms doubts |newspaper=The Guardian |location=London }}</ref> and it was commissioned in 1999.

===Replacement===
{{Main|Dreadnought-class submarine}}

The Vanguard class had an originally intended service life of 25 years.<ref>{{Cite web |last=Service |first=Nuclear Information |date=2023-08-07 |title=HMS Vanguard leaves Devonport after 7 years of maintenance |url=https://www.nuclearinfo.org/article/hms-vanguard-leaves-devonport-after-7-years-of-maintenance/ |access-date=2024-05-28 |website=Nuclear Information Service |language=en-GB}}</ref> This would put the retirement dates for the class at 2018, 2020, 2021, 2024.<!-- Feel free to move this bit somewhere better in the article, but I feel this should at least be mentioned somewhere on this page. -->

On 4 December 2006, then Prime Minister [[Tony Blair]] revealed plans to spend up to £20&nbsp;billion on a new generation of ballistic missile submarines to replace the ''Vanguard'' class. In order to reduce costs and show Britain's commitment to the [[Treaty on the Non-Proliferation of Nuclear Weapons|Non-Proliferation Treaty]], Blair suggested that submarine numbers could be cut from four to three, while the number of nuclear warheads would be cut by 20% to 160.<ref name="WhitePaper">{{citation |url=http://www.mod.uk/NR/rdonlyres/AC00DD79-76D6-4FE3-91A1-6A56B03C092F/0/DefenceWhitePaper2006_Cm6994.pdf|title= The Future of the United Kingdom's Nuclear Deterrent|date=4 December 2006|publisher=[[Ministry of Defence (United Kingdom)|Ministry of Defence]] | access-date =5 December 2006}}</ref> On 23 September 2009, then Prime Minister [[Gordon Brown]] confirmed that this [[Rule of thirds (military)|reduction to three]] submarines was still under consideration.<ref>{{cite news| url=http://news.bbc.co.uk/1/hi/uk_politics/8270092.stm| author=BBC News| title=Brown move to cut UK nuclear subs | access-date=23 September 2009 | date=23 September 2009}}</ref> In February 2011, the [[Secretary of State for Defence|Defence Secretary]] [[Liam Fox]] stated that four submarines would be needed if the UK was to retain a credible nuclear deterrent.<ref>{{cite news| url=https://www.bbc.co.uk/news/uk-scotland-12504517 |work=BBC News  | title=Trident nuclear fleet cuts ruled out by Liam Fox | date=23 February 2011}}</ref> On 18 May 2011 the British government approved the initial assessment phase for the construction of a new class of four submarines, paving the way for the ordering of the first long-lead items and preparations for the main build to begin in the future. This new class of submarine, now known as the [[Dreadnought-class submarine|''Dreadnought'' class]], will retain the current Trident II missiles, and will incorporate a new [[Rolls-Royce PWR#PWR3|'PWR3']] nuclear reactor as well as technology developed for the {{sclass|Astute|submarine|0}} nuclear-powered fleet submarines of the Royal Navy.

A vote on the Trident renewal programme was held in the [[House of Commons of the United Kingdom|House of Commons]] on 18 July 2016, and determined that the UK should proceed with construction of the next generation of submarines. The motion passed with a significant majority of 472 MPs voting in favour and 117 against. The MoD put the cost of building, testing and commissioning the replacement vessels at £31&nbsp;billion (plus a contingency fund of £10&nbsp;billion) over 35 years, or about 0.2&nbsp;per&nbsp;cent of government spending, or 6&nbsp;per&nbsp;cent of defence spending, every year.<ref name="modfeb16">{{cite web|url=https://www.gov.uk/government/publications/uk-nuclear-deterrence-factsheet/uk-nuclear-deterrence-what-you-need-to-know|title=UK nuclear deterrence: what you need to know|publisher=Ministry of Defence|date=26 February 2016|access-date=1 March 2016}}</ref> It is expected the new fleet of submarines will come into operation starting 2028 at the earliest<ref name="auto"/> and certainly by the 2030s.<ref>{{cite news|url=https://www.bbc.co.uk/news/uk-politics-36830923|title=MPs approve Trident renewal|date=18 July 2016|work=BBC News|access-date=18 July 2016|quote=MPs approve Trident renewal|author=<!--Staff writer(s); no by-line.-->}}</ref> The ''Dreadnought'' class will extend the life of the Trident programme until at least the 2060s.<ref>{{cite news|url=https://www.independent.co.uk/news/theresa-may-trident-renewal-nuclear-attack-threat-labour-free-vote-a7141826.html |archive-url=https://ghostarchive.org/archive/20220811/https://www.independent.co.uk/news/theresa-may-trident-renewal-nuclear-attack-threat-labour-free-vote-a7141826.html |archive-date=11 August 2022 |url-access=subscription |url-status=live|title=Theresa May warns threat of nuclear attack has increased ahead of Trident vote|author=Tom Peck|date=18 July 2016|access-date=18 July 2016|work=Independent}}</ref>