THE government was urged to hand over all relevant papers to the child abuse inquiry yesterday after a damning leaked document revealed MI5 and Margaret Thatcher’s administration colluded in a cover-up.

The files show that former MI5 director-general Sir Antony Duff wrote to the then cabinet secretary Sir Robert Armstrong in 1986 over allegations made by two sources regarding an MP “who had a penchant for little boys.”

But Mr Duff warned that “the risks of political embarrassment to the government is rather greater than the security danger,” discounting the child abuse risk.

Napac chief executive Gabrielle Shaw, whose organisation supports survivors of child abuse, told the Star that the fact the documents had only just come to light was “shocking.”

She said: “It is ineptitude at best, and far more suspicious at worst.

“It does not do any favours for survivors when there are whispers of a cover-up and this just adds more fuel to the fire.

“It is good that it has come out now, but you can understand why some people might well be asking: ‘What else has not been handed over?’”

She added that the documents gave “a very disturbing insight into the culture of the times.”

Peter Wanless, head of child protection charity NSPCC, and Richard Whittam QC, who together carried out an inquiry into the handling of historical Westminster abuse allegations, said the documents had reinforced their view that allegations of crimes against children, particularly the rights of the complainant, were given considerably less serious consideration than would be expected today.

The Home Office confirmed that a fresh search of the archives had been carried out after a file emerged earlier this year that should have been submitted to the Wanless and Whittam inquiry.

Former Cabinet minister Leon Brittan, one-time Thatcher aide Peter Morrison, ex-diplomat Sir Peter Hayman and former minister William van Straubenzee were named in other top secret files uncovered following the review.

One of the files relating to Sir Hayman was held by the Cabinet Office but had been “overlooked” during a previous search.

Documents that refer to Mr Straubenzee had been earmarked for destruction, but National Archives officials flagged them up to the government.