Four minute warning

The four-minute warning was a public alert system conceived by the British Government during the Cold War and operated between 1953 and 1992. 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.

The warning would be initiated by the detection of inbound missiles 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. From 1958 to 1963, the radio telescope had the task of giving early warning of a Soviet attack. Plainclothes Royal Air Force officers even worked alongside scientists, engineers, and undergraduates, with only the director, Bernard Lovell, and the Air Ministry knowing who they were. Lovell was angry at this arrangement, saying:

It was known only to a very few people that I had been approached by the Chief of the Air Staff, who told me we had the only instrument in the world that could detect a Soviet missile. I simply wanted to do research, but events wouldn't allow me to.

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 (which could have been as little as thirty seconds from launch to impact on a target). By the 1980s, the warning was to be given on the orders of a Warning Officer from the Home Office's Warning and Monitoring Organization stationed at RAF High Wycombe.

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