The Government’s beleaguered child sex abuse inquiry is threatening to drag up false allegations against Lord Brittan in a move that has caused deep distress to his widow.

The £100 million inquiry has written to Lady Brittan warning her that she is likely to be ‘upset’ by the re-examination of previously discounted allegations against her husband, the former home secretary.

Lady Brittan has already received £100,000 in damages from the Metropolitan Police over a botched investigation into unfounded claims that a paedophile ring existed in Westminster.

But now the Independent Inquiry into Child Sexual Abuse (IICSA) is threatening to dredge up a series of historic claims made against Lord Brittan - despite the fact police have exhaustively investigated and dismissed them.

The inquiry, which has lurched from one scandal to another since its launch, is expected to rake up a series of claims as part of its investigation beginning in March into allegations that senior politicians in Westminster were paedophiles whose abuse was covered up by authorities.

IICSA will also examine a series of claims against Sir Edward Heath, the former prime minister who died almost 15 years ago and cannot defend himself.

A £2 million inquiry into Heath found no corroborating evidence to suggest he had sexually abused children.