A minister who quit Edward Heath's Tory government over a sex scandal told MI5 that he turned to call girls because of the "futility" of his job.
Papers show Lord Lambton's activities had the Cabinet in a spin
Lord Lambton resigned in May 1973 as minister for the RAF after he was
photographed naked in bed with two women and smoking cannabis.
Documents released by the National Archives on Thursday under the 30-year rule show MI5 feared a scandal.
Lambton told them a battle over his father's title had made him "frantic".
Mr Heath had ordered a Security Commission inquiry into the implications of the
affair after Lambton and the Leader of the Lords, Lord Jellicoe, both resigned
within a matter of days after admitting they used prostitutes.
Following his resignation, Lambton told television presenter
Robin Day that he had used "whores for sex" because "people sometimes like
variety. It's as simple as that".
But in an interview with MI5 officer Charles Elwell, Lambton claimed first the pressure of work made him seek out the prostitutes.
"He rather implied that the futility of the job was one of the reasons he had
got up to mischief ('idle hands' etc)," Elwell noted.
Then Lambton claimed it was a fight over an aristocratic title of his father's which had made him lose judgement.
"This had become an obsession with him to the extent that he was no longer
able to read - and he had been a great reader - and he sought to forget his
obsession in frantic activity," Elwell noted.
"He had for example become an enthusiastic and vigorous gardener. Another
example of this frenzied activity was his debauchery."
His activities came to light when the husband of a call girl, Norma Levy, photographed the minister in a compromising position and tried to sell the pictures to Fleet Street.
The government, fearing another Profumo scandal, agonised over what to do about it.
Robert Carr said that it was "not a crime to have a mistress" and that there
was no proof at the stage that Lambton was involved in drugs.
Lambton said he had never taken his red state boxes with him to any trysts at Mrs Levy's home.
A search of his home turned up a small amount of drugs and the minister resigned.
Whitehall was then full of rumours that another minister had also been involved.
Lord Jellicoe was named and approached by Mr Heath's private secretary, Robert Armstrong.
Lord Jellicoe denied he knew Mrs Levy but admitted that he had indeed been using prostitutes but had procured them from the Mayfair Escort Agency.
A report to Mr Heath said: "There is nothing in his conduct to suggest that the risk of indiscretions on these occasions was other than negligible." Nevertheless Lord Jellicoe resigned.
Parts of the documents released from the National Archives on the subject have been blacked out and some are missing.