'He could be perverse both in argument and behaviour, but in the former he would wriggle back to sense and in the latter he would apologise in such an engaging manner that it was difficult to be angry for long.

'His sex life was already fairly full, but he did not blazon it about as he was to do later.'

When they shared a house in central London during the war years, Blunt said: 'It is true that Guy had a number of friends who visited him regularly, but it was a rule of the house that casual pick-up was forbidden and Guy observed this rule.'

After Maclean and Burgess fled to Russia in 1951, Blunt came under suspicion but refused to follow their example because, he wrote: 'I realised quite clearly that I would take any risk in this country, rather than go to Russia.'

He was eventually denounced in 1964 and confessed when offered immunity, giving the authorities 'all the information that I had about the Russian activities'.

He was allowed to return to work -- in exchange for cooperation with the MI5 -- and he continued with the royal post until 1972, saying 'I believed, naively, that the security service would see it, partly in its own interest, that the story would never become public.'

His sudden public exposure by Thatcher, who named him in parliament in 1979, came as an 'appalling shock', he wrote, but he decided not to kill himself: 'Many people will say that it would have been the 'honourable' way out... I came to the conclusion that it would on the contrary be a cowardly solution.'

'It would have made things as bad as possible for my family and friends; they would have had the double shock of my suicide and the revelations which would have followed immediately.'

Instead, he sought refuge in 'whisky and concentrated work' on his memoir and a number of books on art history.

According to the media reports of the time, Blunt went into hiding in Europe after the public shaming.

Returning to London years later, he tried to slip into a cinema in the London neighbourhood of Notting Hill one day, but was recognised and booed until he was forced to leave the auditorium.