Editing Four-minute warning (section)

== The warning system ==

=== Basic details ===
The warning would be initiated by the detection of inbound [[missile]]s and aircraft targeted at the United Kingdom. Early in the [[Cold War]], [[Jodrell Bank]] was used to detect and track incoming missiles, while continuing to be used for astronomical research.<ref>[https://web.archive.org/web/20080725144222/http://www.timesonline.co.uk/tol/news/uk/science/article3253887.ece Jodrell Bank article]</ref>

Throughout the Cold War, there was a conflict between the [[Royal Air Force]] and the [[Home Office]] about who was in charge of the warning system. This was not for any practical or technical reason but more to do with who would be blamed if a false alarm were given or if an attack occurred without warning. By the 1980s, the warning was to be given on the orders of a Warning Officer from the [[United Kingdom Warning and Monitoring Organisation|Home Office's Warning and Monitoring Organisation]] stationed at [[RAF Booker]] near [[High Wycombe]].<ref>[http://www.subbrit.org.uk/rsg/features/sfs/file_16.htm Conflicts over the political fallout explained], subbrit.org.uk</ref>

From the early 1960s, initial detection of attack would be provided primarily by the [[Royal Air Force|RAF]] [[BMEWS]] station at [[RAF Fylingdales|Fylingdales]] in [[North Yorkshire]]. There, powerful [[radar]] would track the inbound missiles and allow confirmation of targets. In later years the first indication of any imminent attack would be expected to come from [[infrared]] detectors aboard the United States [[Defense Support Program]] (DSP) satellites. BMEWS would still play an important role in tracking and confirming the destination of any launches.

The British government was not the main beneficiary of BMEWS, given that it would only receive what [[Solly Zuckerman]] described in 1960 as "no more than 5 minutes warning time" of an attack. The United States was the United Kingdom's most important military and technological partner, and its US-based [[Strategic Air Command]] would have thirty minutes warning from the Fylingdales station, whilst the RAF's own [[V bomber]] force would have about ten minutes.<ref name="baylis1995">{{cite book | title=Ambiguity and Deterrence: British Nuclear Strategy 1945–1964 | publisher=Clarendon Press | author=Baylis, John | year=1995 | location=Oxford | isbn=0-19-828012-2 |page=280}}</ref>

=== UKWMO and the ROC ===
{{Main|United Kingdom Warning and Monitoring Organisation|Royal Observer Corps}}
[[File:Wb1401warning receiver ptreehse.jpg|thumb|right|WB1401 warning receiver]]
It was the responsibility of the United Kingdom Warning and Monitoring Organisation (UKWMO) at the United Kingdom Regional Air Operations Centre (UK RAOC) located at [[RAF Booker]] to alert the nation to an imminent air attack.<ref>{{cite book|url=https://books.google.com/books?id=5ktyqbWssgAC&pg=PT62|title=The Inner Man: The Life of J.G. Ballard|first= John |last=Baxter|publisher=W&N|year=2011|isbn=978-0297863526}}</ref> Once an alert was initiated the national and local [[television]] and [[radio]] networks would break into transmissions and broadcast a warning (the warning message would originate from an emergency studio in [[BBC]] [[Broadcasting House]] in London). Simultaneously the national [[air raid siren]] system would be brought into service. A system, which used the same frequency on normal telephone lines as the  peacetime [[speaking clock]], was employed for this whereby a key switch activation alerted 250 national Carrier Control Points or CCPs present in [[police station]]s across the country. In turn the CCPs would, via a signal carried along ordinary phone lines, cause 7,000 powered sirens to start up. In rural areas, around 11,000 hand powered sirens would be operated by [[postmaster]]s, rural police officers, or Royal Observer Corps personnel (even parish priests, publicans, magistrates, subpostmasters or private citizens could be involved in some remote rural areas).

Linked into the system were the twenty-five Royal Observer Corps (ROC) group controls, also with direct links to the carrier control points. In the event of subsequent radioactive fallout, local fallout warnings could be generated from the group controls on a very localised basis over the same carrier wave system.

The national warning system saw many changes over the years. During the 1960s and 1970s, much of the local authority [[civil defence]] planning in the United Kingdom became outdated, although the WB400/WB600 warning system was maintained and kept serviceable along with updating of ROC instrumentation and communications. The system's main problem was that many of the telephone lines it needed had to be manually switched in times of pre-war tension by Post Office telephone engineers. The links were not hardened against the effects of [[Electromagnetic pulse|EMP]]. In the late 1970s and early 1980s heightened fears and tensions led to a resumption of contingency planning and the upgrading of many systems. The outdated WB400/WB600 systems were replaced with brand new WB1400 equipment, communications links were made permanent and hardened against EMP disruption.

=== Sirens ===
The national siren system originating from [[World War II]] had a secondary role of "general warning", particularly for imminent flooding. Following the end of the [[Cold War]], a telephone-based system was thought to be more appropriate for national warnings and less expensive to maintain.

Additionally the government retains an ability to break into television and radio broadcasts for the purpose of alerting the general public{{cn|date=September 2023}} and has legal power to take over editorial control of the [[BBC]] during a national emergency under the [[BBC Charter]] and the [[Broadcasting Act 1980]].

The national siren system was largely dismantled during the 1990s. The British government cited the increasing use of [[Insulated glazing|double-glazed windows]] (which make sirens harder to hear) and the reduced likelihood of air attack as reasons to eliminate the system in most parts of the country. Some coastal and river areas have retained and regularly test the sirens as part of the flood warning defences. Since 1952, [[Broadmoor Hospital]] has employed [[Broadmoor Sirens|a network of 13 sirens]] to warn of escaped patients; this is tested every Monday at 10 am. The hospital sirens were scheduled for removal during 2018 except for one located in the hospital grounds. [[State Hospital|Carstairs Hospital]] also retains its sirens, which are tested monthly. In some towns, sirens were once used to summon part-time firemen until the introduction of radio pagers during the 1970s – these stand-alone sirens operated independently of the warning network.

Torness nuclear power station in East Lothian Scotland uses two of these sirens as a warning of an off-site nuclear emergency, tested every Tuesday morning at 10.