Tom Watson is under renewed pressure as victims of Scotland Yard’s inquiry into a fictional Westminster paedophile ring urge him to resign ahead of the publication of a report.

The report will explore how false claims made by Carl Beech against politicians and senior military officers led to Operation Midland, which cost £2.5m and falsely accused several high-profile figures of sexual abuse.

The deputy Labour leader is “unfit to hold the office of MP”, according to Lady Brittan, the widow of Lord Brittan of Spennithorne, the former Conservative home secretary who died before the claims against him were proved to be false.

Speaking to The Times, a friend of Lady Brittan said “the extent of Tom Watson’s involvement in the witch-hunt of innocent people has been laid bare” in the report, which is expected to detail Watson’s contact with and influence over the police.

Watson’s “subsequent attempts to distance himself show a complete lack of integrity”, the friend adds. By “misusing his public office to recklessly repeat false allegations, and to characterise himself as a victim, he has shown that he is unfit to hold the office of MP”.

Another former Conservative MP, Harvey Proctor, has also called for the resignation of Watson after reading the report. Proctor, wrongly named a child murderer and paedophile by Carl Beech, who was later convicted of making false claims, says Watson had displayed a lack of judgment.

According to The Daily Telegraph, the report will state that that “bungling” Scotland Yard detectives in charge of the VIP sex abuse inquiry became “so fixated with appeasing Tom Watson they failed to spot the accuser was a serial liar”.

Watson said last night: “I have always said that it wasn’t my place to judge whether sexual abuse allegations were true or false; that was for the police. The police asked me to encourage the hundreds of people that came to me with stories of child abuse to report their stories to the police. That is what I did.”