The four minute warning was a public alert system conceived by the British Government during the Cold War and operated between 1953 and 1992 when the system was dismantled after the cold war finished. The name derived from the approximate length of time from the point at which a Soviet nuclear missile attack against the United Kingdom could be confirmed and the impact of those missiles on their targets. The population was to be notified by means of air raid sirens, television and radio, and urged to seek cover immediately. In practice the warning would have been more likely three minutes or less.
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, fell into diservice, 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; Additionally the links were not hardened against the effects of 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 The outdated WB400/WB600 systems were replaced with brand new WB1400 equipment, communications links were made permanent and hardened against EMP disruption.
However with the end of the Cold War in the late 1980s and early 1990s the national siren system was largely dismantled. The British Government cited the increasing use of double glazed windows, which make sirens harder to hear, and the reduced likelihood of air attack as reasons to eliminate the siren system in most parts of the country; Some coastal areas still retain and regularly test the sirens as part of the flood warning defences.
"This is the Wartime Broadcasting Service. This country has been attacked with nuclear weapons. Communications have been severely disrupted, and the number of casualties and the extent of the damage are not yet known. We shall bring you further information as soon as possible. Meanwhile, stay tuned to this wavelength, stay calm and stay in your own homes. Remember there is nothing to be gained by trying to get away. By leaving your homes you could be exposing yourselves to greater danger. If you leave, you may find yourself without food, without water, without accommodation and without protection. Radioactive fall-out, which follows a nuclear explosion, is many times more dangerous if you are directly exposed to it in the open. Roofs and walls offer substantial protection. The safest place is indoors. Make sure gas and other fuel supplies are turned off and that all fires are extinguished. If mains water is available, this can be used for fire-fighting. You should also refill all your containers for drinking water after the fires have been put out, because the mains water supply may not be available for very long. Water must not be used for flushing lavatories: until you are told that lavatories may be used again, other toilet arrangements must be made. Use your water only for essential drinking and cooking purposes. Water means life. Don't waste it. Make your food stocks last: ration your supply, because it may have to last for 14 days or more. If you have fresh food in the house, use this first to avoid wasting it: food in tins will keep. If you live in an area where a fall-out warning has been given, stay in your fall-out room until you are told it is safe to come out. When the immediate danger has passed the sirens will sound a steady note. The "all clear" message will also be given on this wavelength. If you leave the fall-out room to go to the lavatory or replenish food or water supplies, do not remain outside the room for a minute longer than is necessary. Do not, in any circumstances, go outside the house. Radioactive fall-out can kill. You cannot see it or feel it, but it is there. If you go outside, you will bring danger to your family and you may die. Stay in your fall-out room until you are told it is safe to come out or you hear the "all clear" on the sirens. Here are the main points again: Stay in your own homes, and if you live in an area where a fall-out warning has been given stay in your fall-out room, until you are told it is safe to come out. The message that the immediate danger has passed will be given by the sirens and repeated on this wavelength. Make sure that the gas and all fuel supplies are turned off and that all fires are extinguished. Water must be rationed, and used only for essential drinking and cooking purposes. It must not be used for flushing lavatories. Ration your food supply: it may have to last for 14 days or more. We shall repeat this broadcast in two hours' time. Stay tuned to this wavelength, but switch your radios off now to save your batteries until we come on the air again. That is the end of this broadcast."
The four minute warning was a central plot and narrative device in the BBC drama Threads, about how society decays after a nuclear holocaust, which focuses on an attack on Sheffield. The War Game also portrays the four minute warning, pointing out the warning period could be even less. The narrator, Michael Aspel, says it could even be two minutes between issuing the warning and impact on a target. The film adaptation on Raymond Briggs's satirical and blackly comic cartoon strip, When the Wind Blows, has the warning message as part of the script, which triggers arguing between Jim and Hilda Bloggs. Although this is not Peter Donaldson's pre-recorded warning (which was not available on grounds of national security and for copyright reasons), this was a fictional announcement written on grounds of artistic licence. It was read by Robin Houston, a voiceover artist who was known in London as a newsreader for Thames Television.
The adult humour comic Viz ran a photo strip in its issue 107 called "Four Minutes to Fall in Love", where a boyfriend and girlfriend cram a whole relationship into the four minutes before a nuclear attack. The Four Minute Warning had become the inspiration for many jokes and sketches in comedy programmes in Britain, in the same way that the Emergency Broadcast System had in the United States (see nuclear weapons in popular culture). In one episode of Only Fools and Horses, "The Russians Are Coming," Delboy and Rodney Trotter sell fallout shelter kits and have an attack drill. Driving towards their shelter, they are stopped by the police for speeding and asked: "You just heard the four minute warning?" After being sent on their way, Rodney points out: "We died forty-five seconds ago." Around the same time, a sketch on the BBC Scotland programme Naked Video had a mock announcement warning of an attack with a punchline of "...except for viewers in Scotland."