With threats of a new Cold War marking the lowest point for Anglo-Russian relations in decades, the story of how notorious 1960s spy George Blake escaped from Wormwood Scrubs prison makes for timely reading.

Details released under the Freedom of Information Act show a series of blunders by the intelligence services and prison authorities before the dramatic breakout on October 22, 1966.

Blake, who was born in the Netherlands, was five years into a 42 year sentence at the jail after being found guilty of breaching the Official Secrets Act by betraying dozens of British agents in the Middle East, many of whom are believed to have been executed.

The prison's governors were warned as early as May 1964 about a possible attempt to spring Blake.

But Roger Hollis - the then head of MI5 who was himself later suspected of being a Soviet spy - wrote in a memo that the escape plot was likely to have been fabricated by an unreliable source with 'a history of mental instability' who was 'incapable of dissociating fact and fantasy.'

Hollis reassured the Government that Blake was being watched too closely to attempt a breakout.

Papers show he was viewed as a model inmate who had come to terms with his unusually long sentence.

When a story appeared in the People newspaper claiming an escape attempt had been foiled by another prisoner, Blake - backed by one of the prison governors - demanded a correction, claiming the story had cast doubt on his moral conduct.

Two years later Blake, with the help of three political sympathisers inside Wormwood Scrubs prison, climbed through a window at the end of his prison landing and escaped using a rope ladder.

Prison staff were slow to take action, the deputy governor only managing to call Shepherd's Bush police station afterwards to the fact they had lost 'one of their chaps' over the east wall of the jail, that it was probably Blake and that he was wearing prison grey.

And MI5 were equally slow in tracking down the escaped spy, convinced he had made it to the Soviet Union despite reports of him in the south of France and Bermuda.

A letter to his mother six months after his escape bore an Egyptian post mark, but Blake did ultimately make it to Moscow.

Last year the Russian President, Vladimir Putin, awarded Blake the Order of Friendship, one of Russia's highest honours, for his services to espionage.