Four-minute.

This is coolbert:

"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." - - Sir Bernard Lovell.

Sir Bernard in that particular instance speaking of the Jodrell Bank radio telescope and the secret military mission as was the case from the period of the Cold War.

Part and parcel of what was called the "Four-minute Warning".

Soviet ballistic missiles in-bound toward English targets and carrying thermonuclear warheads that amount of warning for the British command and decision-making establishment a grand total of four minutes!!

"The Four-minute Warning."

"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."

Radio telescopes normally only "listening".  Jodrell Bank and other facilities of a similar nature, at least some of them, also having a capacity [hidden perhaps] on demand to act as a giant radar when needed. That detection of inbound Soviet missiles too only possible when the "dish" pointed in the right direction.

Jodrell Bank yesterday, Chilbolton today? Who knows?

coolbert.