A SECRET document relating to Westminster child abuse allegations and marked for destruction surfaced the day after Sir Leon Brittan died, The National can reveal.

The file came to light in the Cabinet Office archives on January 22 this year – 24 hours after the former Home Secretary passed away.

Its contents continue to be withheld but a newly published letter said the document related to Sir William van Straubenzee, a late Tory minister, and referred to the Kincora Boys’ Home in Belfast – a notorious orphanage at the centre of abuse investigations.

Two other sets of papers – one which explicitly related to Brittan – also suddenly surfaced in the Cabinet Office in the weeks after he died.

Straubenzee, right, a former Northern Ireland minister, was a parliamentary colleague of Brittan, and both men, along with Margaret Thatcher aide Sir Peter Morrison and the diplomat Peter Hayman were named in the two files which emerged soon after Brittan’s death.

Last night, furious campaigners said the discovery of files so soon after a suspect died suggested the Government had attempted to protect senior political figures and cover up allegations about child abuse among the Westminster elite.

Phil Frampton, the national coordinator of survivors group White Flowers, said the uncovering of such a file a day after Brittan died – and of the others over the following weeks – was too much of a coincidence.

He said: “To me it indicates these documents were being deliberately held back while Leon Brittan was alive. It creates a real suspicion the Straubenzee file and the others were kept back until after Brittan’s death in order to protect him.

“The sudden discovery of a child abuse file the day after one of the men implicated dies is far too much of a co-incidence.” He added: “These files should have been brought to the attention of the police while Brittan was alive.

“If they had been he may have been brought to justice. I am outraged and at the same time feel vindicated that this Government has been trying to thwart public demands for justice.”

Alan Draper, parliamentary liaison officer for In Care Abuse Survivors, called for the contents of all the files to be published.

“It is clear the authorities wanted to protect figures in the establishment and put that before protecting children from abuse,” he said. “Children were being used as toys. People say these were different times but sexually abusing children was as much a crime in the 1960s, 70s and 80s as it is today. There is no doubt these men should have been reported to the police.

“The men are now dead and cannot be prosecuted but the public have a right to know what’s in these papers.”

Andi Lavery, an abuse survivor who has formed a group White Flowers Alba, said: “It is totally bizarre that these documents apparently didn’t exist when Leon Brittan was alive, yet as soon as he dies they suddenly come to light. The children who were abused have been forgotten about and what’s going on now is all about protecting reputations and covering backs.”

The revelation about the discovery of the files emerged in a letter from leading Cabinet Office civil servant Richard Heaton to Peter Wanless and Richard Whittam, who last year carried out a review into whether the UK Government covered up historic abuse allegations.

Heaton wrote to Wanless in May this year, apologising for his department’s failure to uncover three important files when the two men were investigating. He explained the search inquiry to uncover them had been flawed.

It is understood the Straubenzee document was found when staff from The National Archives (TNA) were called to the Cabinet Office and found the document on January 22.

“A file about Sir William van Straubenzee was identified in late January 2015,” said Heaton in his letter sent in May this year.

“This file did not meet your search criteria and was part of a batch of files that had been selected for destruction in 2013, before your Inquiry began, as part of our routine records management process.

“To guard against the destruction of historically important records, The National Archives team checks files selected for destruction. As a consequence, on 22 January The National Archives referred the file to the Cabinet Office to be reviewed. On review my team noted that the file contained references to the Kincora Boys’ Home. Roger Smethurst promptly drew this to your attention.”

It added: “The final group of papers about Peter Morrison, Leon Brittan, Peter Hayman, William van Straubenzee and Colin Wallace’s allegations about Kincora were found in a separate Cabinet Office store of assorted and unstructured papers.”

The contents of the papers have still not been revealed but have been shared with the police and will be passed to the Child Abuse Inquiry led by Justice Lowell Goddard.

A spokesman for the Cabinet Office said the explanation for the discovery of the documents was set out in the Heaton letter.

A spokesman for The National Archives said: “As part of the review The National Archives performs a supervisory and governance role. Government departments provide lists to The National Archives for review. TNA officers visit records management teams in government departments to physically review the selection and non-selection decisions, and also provide online advice on the review lists. The decision to select or not to select (and the justification for non-selection) is ultimately the responsibility and judgment of the relevant government department.”