The Cold War spy and traitor George Blake, whose betrayal of secret intelligence to the KGB led to the execution of 40 British agents, was at the heart of a confidential Government appeal to newspaper editors in 1961, according to an official history of the D-Notice system published today.

The D-Notice arrangement in which a senior retired military figure provides guidance to newspapers and broadcasters on stories that might damage national security - launched in 1912 and still in existence today - swung into action when Blake was about to go on trial charged with espionage.

Rear Admiral Sir George Thomson, D-Notice Secretary at the time, wrote a private and confidential letter on May 1 1961 in which he told selected editors that Blake was an MI6 intelligence officer, but he asked them not to reveal this piece of information. Naming MI6 officers was and is banned under the D-Notice rules even, apparently, when a member of the service is secretly working for a hostile foreign intelligence agency, such as the KGB.

The admiral asked the editors that, “if they mentioned any of his [Blake's] published appointments, not to mention this connection, nor MI6’s connection with the Foreign Office”. At that time the existence of MI6 was not officially declared.

Times Archive, 1961: 42 years for man who spied for Russia

George Blake freely admitted that there was not an official document of importance which was not passed to his Soviet contacts

• Spy's wish to promote cause of communism

• Restrictions on press

Related Links

• Putin honours traitor Blake with birthday medal

• MI6 tempts rebel ex-spy back home

• British spy loses secrets in a handbag

The admiral added that there was also “a special reason for the request in this case, in that the lives of MI6 employees are still in danger”.

“The record shows that every editor played ball,” according to Secrecy and the Media, The Official History of the United Kingdom’s D-Notice System, written by Rear Admiral Nicholas Wilkinson, D-Notice Secretary from 1999-2004, and launched by the Cabinet Office today.

On May 4 1961, The Times, according to the paper’s archives, reported that “Blake, British Government official and self-confessed spy and agent for Russia” was sentenced to 42 years in prison. There was a reference to his having served as vice-consul in Seoul in 1950 but there was no mention of MI6.

The official history reveals that the following day, May 5, Reuters informed Admiral Thomson that a West German newspaper was carrying a story that Blake had given information to the Soviets which had enabled them to arrest six agents working for Britain behind the Iron Curtain.

“Thomson (and no doubt MI6) felt it likely this leak had originated from the Soviets in an attempt to gain information. After consulting a few in the media, he asked editors not to publish information from foreign sources that ‘tended to confirm what they have been asked to conceal’,” Admiral Wilkinson writes.

Despite the appeal, The Observer published the German report, and other newspapers felt they could no longer suppress the story. Admiral Thomson acquiesced, telling the managing editor of one paper that the D-Notice “had already almost achieved its object [although] there are still one or two agents in jeopardy [almost all the remainder of those who had survived Blake’s treachery having by then been moved to places of safety by MI6],” Admiral Wilkinson reveals.

However, there were considerable doubts expressed subsequently over whether the D-Notice method of suppressing information had worked effectively.

Sir Dick White who was then Chief, or ‘C’, of MI6, is quoted in the official history as saying: “So long as it is merely a question of a few foreign newspapers playing a British story, international repercussions are not likely to be great. Once the British press is unleashed, with all the domestic repercussions and furore that this entails, the international repercussions immediately become very much greater.”

Blake’s treachery had been exposed by a Polish defector in 1959 who informed the CIA that he was a spy for the Soviets whose information had led to the death of “at least 40 agents in Warsaw Pact countries”.

Blake escaped from Wormwood Scrubs in 1966 and turned up in Moscow where he has lived for 43 years.

In 2007, he was awarded the Order of Friendship on his 85th birthday by Vladimir Putin, then Russian President.

Explore UK News

• Crime News

• Education News

• Health News

• Scotland News

Times Recommends

• Times Christmas appeal: Letter from the Editor
• Conferences — what a waste of money
• Schools supremo learns a painful lesson