Lord Brittan, pictured, was falsely accused of raping a woman in 1967 who was a Labour Party activist

A woman who falsely claimed Leon Brittan raped her in 1967 is a veteran Labour activist with mental health problems.

The Tory grandee went to his grave under a cloud of suspicion that he was responsible for a sordid sex assault.

Scotland Yard exonerated him five months after his death following a drawn out inquiry. It found ‘absolutely no evidence’ to support his accuser’s account.

Now it can be disclosed the woman, known by the pseudonym Jane, may have had a political motive because she is a Labour activist who admits hating Tories.

She has endured a troubled life which has included bouts of severe depression, paranoid delusions, relationship problems and various referrals to psychiatrists.

Prior to her allegations about Lord Brittan, she had previously suspected – also wrongly – that a close relative was a paedophile.

Yet despite her mental health problems, and the absence of any supporting evidence, Scotland Yard spent two and half years probing her claims. Lord Brittan was interviewed under caution following political pressure.

Disturbing details of how the Met handled the allegation against the peer, who died in January aged 75, can be revealed as a row rages over the force’s investigation into claims that a VIP paedophile ring murdered three boys in the 1970s and 1980s.

Privately, a number of detectives have ‘grave doubts’ about the testimony of the key witness behind the extraordinary allegations.

The man, known only as Nick, claims he was abused by a murderous paedophile gang including D-Day hero Lord Bramall, ex-prime minister Sir Edward Heath, ex-home secretary Lord Brittan and former heads of MI5 and MI6. But police have found no credible evidence to substantiate his account. The VIP murder probe continues amid claims that politically correct Met chiefs are ‘too scared’ to shelve it. Insiders concede, however, there are clear parallels between the Met inquiries into the allegations of Nick and Jane.

Like Nick, Jane had close dealings with Labour deputy leader Tom Watson and a controversial ‘investigative’ news website.

In May last year, Jane told the Sunday People she was raped by Lord Brittan as a 19-year-old student. The woman said the peer – then in his late 20s and a rising star in the Conservative Party – raped her at his London home after they went on a blind date. She reported the alleged attack to police in late 2012 when detectives opened the probe into an alleged VIP paedophile ring.

In an interview she claimed: ‘It lasted just a few minutes. But they were long moments in my life. It was dark in the bedroom, and I could not see much. I remember him on top of me being very forceful.’

Legal sources confirmed there was no evidence to support Jane’s claims. Nor was there any proof that she had even met the former home secretary.

Both 'Nick' and 'Jane' had close dealings with Tom Watson, pictured, and an 'investigative' news website

The exhaustive investigation, which included tracking down key witnesses and examining Lord Brittan’s job and domestic arrangements at the time of the alleged offence, undermined his accuser’s story. Lord Brittan was questioned in June last year shortly after Mr Watson complained to the Director of Public Prosecutions that the case was not being handled properly.

Prior to his intervention, the CPS had concluded there was insufficient evidence to prove a rape offence – even if the woman had met Lord Brittan.

In his letter to the DPP, Mr Watson described the alleged rape victim as a ‘very credible witness’.