The British government sought to withhold evidence that former Prime Minister Margaret Thatcher knew about claims the senior Liberal Democrat politician Cyril Smith abused teenage boys during the 1960s, but decided to award him a knighthood anyway, it has emerged.
The evidence was acquired by the Mail on Sunday after an 11-month Freedom of Information battle with the UK Cabinet Office, which had resisted the release of the material. But the department is still refusing to make public four other files related to the slow-burning scandal over the sexual abuse of children by establishment figures.
Now, Smith's successor as member of parliament for the northern town of Rochdale has accused Prime Minister David Cameron and Deputy Prime Minister Nick Clegg — of Thatcher's Conservative and Smith's Liberal Democrat parties respectively — of engaging in a cover-up ahead of May's general election.
Simon Danczuk, a Labor politician who exposed Smith as a child abuser, said it was now "absolutely clear" that Thatcher had while prime minister "turned a blind eye to people who were quite clearly pedophiles," describing the revelations as "a real stain on [her] legacy."
He told Sky News on Monday he believed the government was refusing to divulge documents relating to the establishment abuse scandal because it feared revelations that could impact the May vote.
"[The Cabinet Office] have resisted publishing these documents for over 12 months — that's not acceptable."
It was only possible to conclude that they were attempting to cover up such information, Danczuk said. "The reality of it is, this is the truth of the matter, we are approaching the General Election. This isn't party political, but they are concerned about what information is going to come out before the General Election, that's the truth of it."
They were also worried about protecting legacies of former politicians, he suggested.
The government relented in its fight with the Mail on Sunday after it became clear that a minister would have been compelled to defend the decision in court.
In a statement to the newspaper, the Cabinet Office apologized for the delay in releasing material, saying: "It has taken some time to consult all relevant officials."
The Mail on Sunday said further documents had been denied to it "on grounds of national security."
But the brother of a boy who disappeared in 1979 aged 15, and who suspects an alleged Westminster pedophile ring of involvement in the disappearance, told Sky News the decision to keep the files secret was "disgusting".
VICE News has previously reported that on at least three other occasions Thatcher was said to have been alerted to sexual abuse of minors by senior establishment figures, and done nothing about it.
Allegations of which Thatcher is said to have been aware include those focused on diplomat and spy Peter Hayman, and two of Thatcher's closest confidants, Keith Joseph and Peter Morrison.
Smith was a flamboyant, morbidly obese luminary of the Liberal Democrats — currently the junior partner in the ruling Conservative-led coalition — and its predecessor the Liberal Party.
Danczuk has written a book on Smith, his abuse of children, and his iron grip on his northern constituency town.
Although many of his constituents adored Smith, with his bonhomie and his common touch, the allegations were so widely known in Rochdale during the 1970s that parents would tell misbehaving children that unless they were good "Uncle Cyril" would come and get them.
Police in Lancashire, the county in which Rochdale sits, carried out several investigations into Smith in the 1960s, compiling a 80-page file in 1970.
According to Channel 4, which acquired a copy, "in the file, police complain of veiled threats from local Liberals. Smith himself is accused of pressurizing local Liberals to withdraw their statements. The then local MP Jack McCann even spoke to the director of public prosecutions on Smith's behalf, and shortly afterwards, the case was dropped."
At the time, Smith, like McCann, was a member of the Labour Party.
The file was transferred to Lancashire Special Branch. MI5 then learned of the file, and demanded that it be sent to them by special courier. Neither MI5 nor Special Branch took further action against Smith.
"MI5 and Special Branch buried his crimes", Channel 4 concluded.
According to the government documents obtained by the Mail on Sunday, a copy of the dossier had found its way to the Sun newspaper by 1982, a fact revealed by a burglary carried out by an unspecified party.
The press office for Liberal Party leader David Steel — now a lord — said at the time, "all he seems to have done is spanked a few bare bottoms."
Steel took no disciplinary action against Smith. Lord Steel has said that the allegations of which he was made aware were limited to corporal punishment, which was not illegal at the time.
In interviews with the Daily Telegraph and Radio 4, Steel is not reported to have addressed why he thought that Smith's admission that he conducted "medical examinations" on young boys were not cause for further action.
Despite Steel's comments and the "veiled threats from local Liberals" referred to by Channel 4, Liberal Democrat leader and Deputy Prime Minister Nick Clegg has refused to open an internal party inquiry.
"My party, the Liberal Democrats, did not know about these actions. It's up to the police," he said.
It was Steel who recommended Smith for the knighthood, which he received in 1988.
Smith was also named in a separate dossier handed to the journalist Don Hale by the prominent Labor politician Barbara Castle. Hale has said that Smith turned up at his office in person and said that it was "all poppycock."
Hale was subsequently confronted by officers from Special Branch, who seized the file, and warned him that he would be prosecuted if he repeated the allegations.
The papers acquired by the Mail on Sunday include a letter from the then cabinet secretary to the director of public prosecutions asking "whether the case against Mr Smith was not well founded: or whether it was a sound case, but that the evidence was not likely to stand up in court." No reply was included in the disclosed material.
Cyril Smith died in 2010. Police have since taken testimony from at least seven witnesses who say they were physically and sexually abused by Smith.
In a separate development in the long-running scandal, police raided four properties on Wednesday last week, including two homes which belonged to Thatcher's former home secretary, Leon Brittan.
Brittan has been reported to have been a participant in "abuse parties" which took place at the Dolphin Square flats in West London during the 1980s.
Three witnesses have reportedly identified the same former cabinet minister as a participant in the abuse.
Associates of Brittan, who died in January, have denied the allegations.
Also searched by police on Wednesday was the home of the former head of the Armed Forces, Lord Edwin Bramall, and the home of the former Conservative MP Harvey Proctor.
It is not known how either man is connected to the inquiry.
Speaking outside his home on Thursday, Proctor denied any connection to the allegations being investigated by the police's Operation Midland, which carried out the search.
"I have not been part of any rent-boy ring with cabinet ministers, other members of Parliament, or generals, or the military," he said.
Lord Bramall, who oversaw Britain's role in the Falklands war, told the BBC he was "mystified" by the police search.
Follow Tom Dale on Twitter: @tom_d_