A review into how the Home Office handled allegations of historical child abuse has not been able to recover missing documents said to include the names of paedophiles with links to the British establishment.
The secret files, named the Dickens Dossier, were passed on to the then Home Secretary Leon Brittan by Tory MP Geoffrey Dickens in 1983.
The review of how the government handled these allegations, set up and by led by NSPCC chief executive Peter Wanless, was called after the Home office revealed they had "lost or destroyed" 114 documents concerning child abuse allegations.
It is believed the documents handed onto Brittan contained the names of politicians and senior policemen who were suspected of being child abusers
A source close to the Wanless report told BBC's Newsnight they have not been able to find the documents despite looking "inside and behind every single cupboard in the department".
"They have been round them twice, and they have not been able to find any of them," the source added.
Labour MP Simon Danczuk, who is urging Brittan to reveal what he knew about allegations there were paedophiles in Westminster, added: "I am worried Peter Wanless has been set up to fail in many respects.
"I don't think he was given enough time to carry out this investigation. I don't think he was provided with enough support within the Home Office and I am worried he didn't get the technological support.
"I think there are some fairly sophisticated forensic techniques that could have been used to establish what documents were available over a 20-year period and I don't think he has been given the opportunity to get to the documents."
The review is being published as a wider inquiry into historical child sex abuse gets under way despite two of its chairs stepping down.
Ceremonial Lord Mayor of London Fiona Woolf eventually stepped down as the chairman of the inquiry amid increasing pressure because of her links Brittan.
Her predecessor, Baroness Butler-Sloss, also stepped down due to concerns about her relationship with the establishment as her late brother, Lord Havers, was the attorney general in the 1980s.
The current Home Secretary Theresa May apologised to the victims involved in the inquiry following Woolf's resignation.