Anthony Gilberthorpe says he sent her a 40-page dossier in 1989 accusing Cabinet members ofabusing underage boysat drug-fuelled conference parties.
Mr Gilberthorpe, who claims he was ordered to recruit boys for the ministers, says he posted the “graphic” allegations to Mrs Thatcher after befriending her.
Mr Gilberthorpe, who wasa young Tory hopefulwhen he was asked to recruit for the parties, said: “I outlined exactly what I had witnessed and informed her I intended to expose it.
“I had met Mrs Thatcher on several occasions and even presented her with a birthday cake in 1983. I believed she had to know.”
He said that being overlooked for the safe Tory seat of Gloucester in April 1986 made up his mind to shop the ministers. “I believe I was stitched up and it gave me an insight into the treacherous nature of the party,” he added.
“It was one of the reasons I decided reveal what I’d witnessed.I made it very clear to Mrs Thatchermost trusted ministers had been at these parties with boys who were between 15 and 16.
“I also told her of the amount of illegal drugs like cocaine that were consumed.
“I underlined the names of Keith Joseph, Rhodes Boyson and one MP still serving today. I also said I had seen Michael Havers at a party in Blackpool held at the hotel pool in 1983.”
At the time Sir Keith Joseph was the Education Secretary and hailed as the “founding father of Thatcherism”. He died in 1994 aged 76. Sir Rhodes Boyson held several ministerial posts in his career. An advocate of corporal punishment in schools, he died in 2012 at 87.
Mr Gilberthorpe says he received no response from No10 – but was called to a meeting at a House of Lords tearoom with William Hague, who had replaced ex-Home Secretary Leon Brittan as MP for Richmond in North Yorks.
Mr Gilberthorpe, now 52, said: “I have no idea why William Hague was chosen to deal with my allegations.
“He introduced a high ranking civil servant who was also there. Then the civil servant turned to me and said, ‘Now what is this all about?’ I felt very uncomfortable and surrounded, so I loudly told them, ‘What this is about is the way I’m being treated’.”
Gilberthorpe says he then was ushered into a nearby private room.
He said: “The civil servant told me ‘I’ve been made aware of your letter and the very serious allegations in there. Can you substantiate any of the claims?’ I told him I was flagging up things I had seen. He then said ‘Why you are writing to the Prime Minister about these matters is beyond me’.
“I was asked if there was any evidence and I told him it would emerge in time. The civil servant then said ‘What you’ve said is extremely libelous and slanderous. This meeting is finished’.
“Mr Hague hardly said anything. I was ushered out and that was that. I was angry. I thought I’d hit a brick wall and there seemed no other place to go.”
A source close to Mr Hague yesterday said the Foreign Secretary “has no recollection of ever meeting this individual”.
Mr Gilberthorpe has a picture of them both together at Mr Hague’s private office in 2003 where he had hoped to raise the matter again but decided against it.
The source said Mr Hague would not remember as he does “tens of thousands of these grip and grin photographs”.
Last night the civil servant, who we are not naming, did not reply to requests for a comment. Meanwhile speculation is growing over claims Mrs Thatcher must have been aware of rumours about ministers and under-age boys.
Her former Parliamentary Private Secretary Sir Peter Morrison has already been named in connection with a probe into the Bryn Estyn children’s home in Wrexham where Jimmy Savile allegedly molested boys.
The late MP Geoffrey Dickens also passed a list of names of prominent government figures involved in child sex abuse to Mrs Thatcher’s Home Secretary Leon Brittan. The list was “lost” by the Home Office.
Details of Mr Gilberthorpe’s evidence emerged as retired judge Baroness Butler-Sloss came under growing pressure to stand down as head of the Westminster child abuse inquiry.
She is accused of keeping allegations about a bishop out of a review of how the Church of England dealt with two paedophile priests because she “cared about the church.”
In a statement yesterday, Lady Butler-Sloss insisted that she has “never” put the reputation of an institution ahead of justice for victims.
In another development yesterday a former social services official said his warnings about the threat of a Westminster-based paedophile network were ignored because “there were too many of them there”.
David Tombs said he alerted the government after the arrest of paedophile Peter Righton in 1992.
Mr Gilberthorpe, is frank about the battles he has fought with bankruptcy and depression and frustrations over his failed political ambitions.
Last night he said: “Yes, I was very angry about how the Tory party had used me and then later snubbed me. But none of that alters what I saw.
“Yes, I have had my fair share of issues and problems in the past but it doesn’t change what happened and what I saw those men doing.”
Iron Lady and acolytes paraded ‘family values’
A key part of the Thatcher era was her emphasis on “family values” and personal morality.
As a grocer’s daughter, the iron lady talked about running the country’s finances like a thrifty housewife. But she also believed that victorian family values, in the form of a conventional family, hard work and moral strength, were key routes to success.
One infamous example of her intervention into the world of morality and sexuality was section 28 of the 1988 local Government Act.
The hated clause decreed councils must not “promote the teaching in any maintained school of the acceptability of homosexuality as a pretended family relationship”.
ironically, the rule was passed at around the same time the former PM’s Parliamentary Private secretary, the late sir Peter Morrison, was indulging his sexual appetite for boys as young as 15. He is now embroiled in the historic allegations of child abuse at the heart of Westminster.
Her hardline approach was echoed by her ministers, like the late sir Rhodes Boyson who was a fierce opponent of homosexuality.
The twice-married former headmaster, who supported caning for pupils, declared being gay was “unnatural” and “biblically wrong”.
At the height of fears over Aids, ex-lay preacher sir Rhodes said; “if we could wipe out homosexual practices, Aids would die out.”
Baroness was appointed to previous abuse inquiry by brother
The retired judge leading the Westminster abuse probe has revealed she was appointed to run a previous sex abuse inquiry by her late brother, Lord Havers, when he was Lord Chancellor.
Baroness Butler-Sloss has been under scrutiny over her suitability to investigate claims of a child-sex ring at Westminster because of a potential conflict of interest over her Establishment connections.
Yesterday, it was claimed she had kept allegations about a bishop out of a report on a paedophile scandal because she “cared about the church”.
Now, she faces fresh criticism over her admission of the key role of Lord Havers in the Cleveland child sex abuse inquiry in 1987 which she led.
Asked who instigated the Cleveland inquiry in 2003 Lady Butler-Sloss replied: “I think it was my brother actually as Lord Chancellor.”