GCHQ's secret hilltop site in Scarborough revealed as having pivotal role in Cuban missile crisis

The pivotal role in the Cuban missile crisis played by a secret outpost of GCHQ in Scarborough has been revealed.

The task of the tiny bunker on the North Yorkshire coast, described by staff as dank and often smelly, had been to monitor the Soviet Baltic fleet and merchant shipping in the northern hemisphere.

In 1962 this somewhat unglamorous job for Britain’s cyber spy agency was thrust into the centre of world affairs as tensions between the West and the Soviet Union threatened to escalate into nuclear war.

On October 16, 1962, US President John F Kennedy had been told the Soviet Union was secretly shipping nuclear missiles to Cuba, just 90 miles off America’s south eastern coast.

US forces established a naval blockade, preventing the arrival of any ships, but some Soviet vessels were already on their way to the island. Any confrontation between the two naval forces risked escalation into nuclear war.

The operators in the Scarborough bunker were able to intercept the Soviet ships reporting back their position and establish where they were heading.

"Traditionally just another task at the bottom of Scarborough's priority list, suddenly escalated to the very top priority for British intelligence," Tony Comer, GCHQ's historian told the BBC.

“Were the Soviets going to call Kennedy's bluff or not? Scarborough was the organisation that was able to say exactly where these vessels were, when they stopped sailing towards Cuba and when they turned around and headed back to the Soviet Union," Mr Comer added.

The role of the secret hilltop site overlooking the North Sea is the focus of the first part of a BBC Radio 4 series called The Secret History of GCHQ. It reveals how staff were strictly controlled for security purposes.

"The room was full of people, headphones on,” one veteran staff member explained. “Your role was to not miss a beat."

The current director of the base, like other staff, still only gives her first name to protect identities.

"If you wanted to go to the toilet, you had to put your hand up, somebody's got to come in and take your place," Sheila said.

Alongside the work at Scarborough, Britain made two further contributions that helped President Kennedy formulate his strategy during the crisis.

First, the British ambassador in Washington, David Ormsby-Gore, a close friend of President Kennedy, was accorded the unprecedented privilege of sitting in on sessions of the National Security Council.

On October 23, he made a crucial suggestion: that the proposed "quarantine line" of the American naval blockade be modified from 800 miles to 500 miles off the Cuban coast. This notable British proposition would give the Soviet ships approaching from Europe more time to react, and provide Russian President Khrushchev with a face-saver.

The second British contribution was revealed in 1993 when government documents were released under the 30-year rule.

They showed that at the height of the crisis, Prime Minister Harold Macmilan had offered to give up some of Britain’s nuclear weapons in exchange for Soviet withdrawal of missiles from Cuba.

“I feel sure that a long period of blockade, and possibly a Russian reaction in the Caribbean or elsewhere, will lead us nowhere,” Macmillan had said in a personal telegram to David Ormsby-Gore on the day the US imposed a naval blockade.

The declassified papers revealed a personal note from Macmillan to Kennedy in which he had said: “I put the proposal that it might be helpful to save the Russians' face if we undertake during the same period (that Soviet missiles are withdrawn) to allow the immobilization of our Thor missiles, of which there are 60, under UN supervision”.

The offer was not taken up.

The crisis was resolved when President Khrushchev "blinked". He sent a telegram proposing that, if America would promise not to invade Cuba, he would pull out the missiles. It was, in Macmillan's opinion, "a complete capitulation".

The GCHQ base at Scarborough was established just before the First World War because its position was ideal to intercept German naval radio signals in the North Sea.

During the Second World War it helped locate German U-boats in the Atlantic and shifted its focus to monitoring Soviet communications in the years of the Cold War. It is still a functioning GCHQ location.

Part one of The Secret History of GCHQ is on BBC Radio 4 on Monday October 21 at 20:00 BST and on BBC Sounds.