A top British diplomat was the focus of a secret Government file about his 'unnatural' sexual behaviour, it was revealed today.

The file, which has just been released to the National Archives, names the late Sir Peter Hayman as the subject of a file prepared for then-Prime Minister Margaret Thatcher.

Sir Peter died in 1992 after a career working as a diplomat including as High Commissioner to Canada. He also worked for intelligence service MI6.

He was outed as a paedophile in the House of Commons after being let off with a police caution despite being found with a trove of extreme pornographic images which he shared with other child abusers.

Sir Peter Hayman, former British diplomat involved in Old Bailey paedophile case

He was named as a child abuser by the campaigning MP Geoffrey Dickens in the 1980s. He also had links to the controversial Paedophile Information Exchange which campaigned for sex with children to be legalised.

The top secret Government file was retained on grounds of national security and held by officials at the Cabinet Office, until it was finally released by the National Archives today, Sky News reported today.

Sir Peter's sickening secret life was discovered in 1978 after police raided a flat he kept secret from his wife where they found child abuse images and post shared with other paedophiles.

Among it was a library of 45 substantial diaries in which Sir Peter had recorded in detail his sexual experiences and fantasies, the latter including sex with minors.

There was also substantial correspondence with other PIE members — 111 pages in one instance — in which they shared their otherwise secret desires and other graphic paedophile material.

Police later found that two of the dozen or so paedophiles in Sir Peter's circle had been writing to each other about their interest in the extreme sexual torture and murder of children.

Even the hardened cops of the Obscene Publications Squad were 'revolted' by the Linden Gardens haul, it has been revealed.

When interviewed, Sir Peter — a man who had been deputy commandant of the British zone in Berlin and was later tasked to tear a strip off the Soviet ambassador to London after Moscow crushed the Prague Spring of 1968 — broke down and wept.

However, he was let off with a caution.

The Director of Public Prosecutions deemed that as the paedophile material sent through the post by Sir Peter and his friends had not been 'unsolicited' nor traded for profit, no offence had taken place worthy of prosecution.

Sir Peter Hayman and Lady Hayman at Uxmore House, their home in Checkendon. They posed for pictures at the front door, but refused to answer questions concerning child pornography case

Tory peer Lord Brittan was handed a dossier of child sex abuse allegations by the campaigning MP Geoffrey Dickens - who outed Sir Peter Hayman as a paedophile

Sir Peter's reputation remained intact until he was outed in Parliament by the campaigning MP Mr Dickens.

The Hayman affair came back into the spotlight last year after Theresa May ordered an investigation into the alleged cover-up of a VIP paedophile ring which included leading figures in Westminster and Whitehall.

It came after Labour MP Simon Danczuk raised the matter in the Commons and centres on a dossier of child sex allegations involving senior Establishment figures, which was handed to the then Home Secretary Leon Brittan by fellow Tory MP Geoffrey Dickens in November 1983.