Theresa May has asked advisers to examine whether files alleging abuse by senior figures in the 1980s were ever passed to the security services

Theresa May made the extraordinary admission that there ‘might have been a cover-up’ of an Establishment paedophile ring by the Home Office in the 1980s.

The Home Secretary’s comments came after the publication of a report into how her department handled papers relating to alleged Westminster child abusers.

NSPCC boss Peter Wanless and Richard Whittam QC had tried to track down 114 files that went missing in the Home Office.

Just one was found; another was shredded by the Ministry of Justice, which took possession of the dossier, just three years ago.

The men concluded: ‘It is ... not possible to say whether files were ever removed or destroyed to cover up or hide allegations of organised or systematic child abuse by particular individuals because of the systems then in place.

'We cannot say that no file was removed or destroyed for that reason.’

Their report also revealed the list of names which officials were asked to search under when looking for the missing files – suggesting possible links to the so-called Dickens dossier.

It included known paedophiles such as Cyril Smith and members of the Paedophile Information Exchange, which campaigned to legalise sex with children.

It also featured senior political figures such as former Home Secretary Leon Brittan, Labour peer Lord Janner, and two Tory grandees, Sir Peter Morrison and Sir Peter Hayman, who are both now dead.

Police have questioned Lord Brittan and searched Lord Janner’s home in recent months, but neither has been charged.

In a statement to MPs, Mrs May said of the latest findings: ‘It doesn’t prove or disprove the Home Office acted appropriately in the 1980s.’ She added: ‘There might have been a cover-up.’

However, contradicting the Home Secretary and the findings of the report, David Cameron said on the campaign trail in Rochester that ‘conspiracy theorists’ would have to ‘look elsewhere’.

He added: ‘I think it is important that [the report] says there was not a cover-up.’ Last night, Mr Wanless said his comments were ‘wrong’.

The new report centred on the work of late Conservative MP Geoffrey Dickens, who wrote to Lord Brittan in 1983 to say he would expose eight public figures suspected of child abuse unless action was taken.

Lord Brittan has said in a statement that he ‘told Mr Dickens that I would ensure that the papers were looked at carefully by the Home Office and acted on as necessary’. The files were never published.

Earlier this year, amid revelations in the Mail about Smith and the PIE, it emerged that the Dickens dossier had gone missing, along with a string of other documents.

NSPCC chief executive Peter Wanless has carried out a review into Home Office handling of historic allegations of child abuse

Former Tory MP Geoffrey Dickens (left), who died in 1995, said he gave details of Establishment paedophiles – known as 'Dickens dossier' – to then Home Secretary Leon Brittan (right) in 1983

After an initial review by the Home Office found they could not be traced, Mrs May appointed Mr Wanless and Mr Whittam to conduct a full trawl across Whitehall.

Yesterday, the two men said one file had come to light as a result of ‘heightened awareness’ of the subject in the Home Office – but none of Dickens’ were found.

The report also failed to rule out a whistleblower’s claims that the Home Office directly awarded tens of thousands of pounds of public money to the PIE.