Lord Janner’s family lawyer has been compelled to submit a 9,000-word rebuttal of charges brought against him before his death last year, blasting the claimants as “transparent” liars.

In a staunch defence sent to the Goddard Inquiry late last week, solicitor Michael Pether of BLM also took aim at Leicestershire Police for their role in the child sex abuse scandal to have engulfed the late peer.

Many alleged victims of Janner are bringing a civil claim against his estate, after criminal proceedings were ended following a ruling that, due to advanced dementia, he was unfit to stand trial.

The Independent Inquiry into Child Sexual Abuse, led by New Zealand judge Dame Lowell Goddard, will look more widely at institutional failings, and asked Janner’s family to submit evidence that would “undermine” claims against him.

However, the family are concerned that any ruling on Janner as part of the Goddard Inquiry could prejudice the civil claims being made against him.

Of Janner’s family – comprising Senior Reform rabbi Laura, leading QC Daniel, and celebrated mental health campaigner Marion – Pether writes: “What they knew of their father’s professional and personal life totally contradicts the allegations. To them the allegations are an extraordinary abuse of an exceptional, compassionate, kind and unique person.”

Pether said the family were concerned that “very significant public figures” had rushed to “condemn their father in a forensically undisciplined fashion, without knowing the facts,” and that witnesses were “obviously problematic”.

A 9,000-word document, Pether says Leicestershire police were swept up in a “moral panic” and failed to consider “strong evidence” of collusion between complainants, who he accuses of telling “transparent” lies.

“The uninhibited language used in encouraging ‘victims’ to tell their stories has swung the pendulum too far, and the climate of opinion has been too accepting in treating different cases as similar,” he said.

The lawyer acting for the claimants reacted angrily to Pether’s assertion that alleged victims were lying about their abuse as children in order to win money.

“To suggest that Janner’s alleged victims are driven by compensation is a wilful misrepresentation of the situation,” said Liz Dux of Slater and Gordon, speaking to The Sunday Times.

“They are driven by the pursuit of justice and truth. None of my clients even thought about a civil action until a decision was made not to prosecute him. When he died the civil jurisdiction provided the only opportunity they had to prove their very serious claims.”

Janner’s family, who are not giving interviews, have steadfastly maintained that their father was innocent of all charges.

The former Labour MP, investigated for child sex abuse four times, was first accused in 1991. In 2015, police said Janner should be prosecuted on 22 counts of indecent assaults and buggery, against nine persons between 1969 and 1988, but the Crown Prosecution Service ruled him unfit to stand trial.