But Mark Sedwill, permanent secretary to the Home Office, has now admitted for the first time that his department had destroyed, lost or simply "not found" 114 "potentially relevant files".
He also said four new possible leads about child abuse had now been passed on to Scotland Yard.
A senior Tory MP and former children's minister accused the Home Office of a cover-up. Now Theresa May, the Home Secretary, is under pressure to "get involved" in establishing what happened to the missing records. She will face demands in the House of Commons to explain how her department came to lose the documents.
In recent days fresh questions have emerged about whether enough was done to investigate the allegations.
Sedwill wrote to Prime Minister David Cameron yesterday to say a new investigation would examine whether the conclusions of last year's review "remain sound".
But in a separate letter to Keith Vaz, the home affairs select committee chairman, he outlined new details about the 2013 review, in which he made the admission about the 114 files.
In his letter, Sedwill told Vaz that Dickens had submitted allegations of sexual offences over a number of years to several home secretaries, including Brittan, rather than just one single dossier.
He said the review had analysed a central database containing 746,000 files from the period 1979 to 1999 and had identified 527 potentially relevant files, from which nine items of information about alleged child abuse were reported to police.
But Sedwill said the same analysis of the central database "identified 114 potentially relevant files had been presumed destroyed, missing or not found".
The admission immediately raised further questions as to whether there was an attempt inside Whitehall to cover up the allegations raised by Dickens when he submitted his dossier to Lord Brittan.
Vaz welcomed the decision to set up a new review of the Government's handling of the cases but expressed deep concerns about the loss of so many files.
"It is a huge amount of files about a very sensitive issue. We really need to know who authorised it. How do we know such a precise figure? Somebody must have known that these 114 files existed and they must presumably know the date that they went missing or were destroyed. We know the Home Office loses passports and a couple of files here or there but 114 is quite a lot of files to lose."
Tim Loughton, former Conservative children's minister, said: "To lose one file is unfortunate but to lose 114 smacks of complete incompetence or, I fear, some degree of cover-up."
The Home Office said the original review was satisfied it had passed to the appropriate authorities information about child abuse which was "credible" and "had realistic potential for further investigation". But it admitted that for the conclusions to "remain valid" a new examination of its work by a senior independent legal figure was required.
Dickens, who died in 1995, told his family details in his dossier would "blow the lid off" the lives of powerful and famous child abusers, his son Barry said.
Brittan has confirmed he received a "substantial bundle of papers" from Dickens when he was Home Secretary in 1983 and said he had passed them to his officials for investigation.
May said she would "examine the case" for a public inquiry into historical child abuse in public life, for which 139 MPs have now called.
More than 10 current and former politicians are on a list of alleged child abusers held by police investigating claims of a Westminster paedophile ring.
MPs or peers from all three main political parties are on the list, which includes former ministers and household names. Several are no longer alive, but others are still active in Parliament.
The existence of the list was disclosed by Peter McKelvie, a retired child protection team manager and whistleblower whose claims prompted Operation Fernbridge, the Scotland Yard investigation into allegations of a paedophile network with links to Downing Street.
