Lord Greville Janner has been suspended from the Labour Party.

Lord Greville Janner has been suspended from the Labour Party.

The decision not to charge Lord Janner over alleged child sexual abuse could lead the public to see any investigation into the establishment as a “whitewash”, a group of senior politicians has warned.

The former Labour peer, 86, was deemed by the Crown Prosecution Service (CPS) to be too unwell to stand trial because of his dementia, sparking anger from his alleged victims.

A cross-party group, co-ordinated by Labour’s Simon Danczuk, claimed in a letter to the Times that the decision was “damaging public confidence” in the justice system and called for Director of Public Prosecutions Alison Saunders to prosecute.

The letter, co-signed by politicians including Conservatives Zac Goldsmith and Nadine Dorries, Ukip’s Mark Reckless and Caroline Lucas, of the Green Party, said: “Have we learnt anything from the mistakes of the past?”

“As long as justice is not seen to be done and the greater public interest is not served, the public will see attempts to investigate establishment figures involved in historic child abuse as a whitewash.

“The CPS has acknowledged the case against Lord Janner passes its evidential test, and there are established precedents in proceeding with cases against defendants with advanced dementia.

“Defendants have been charged with child abuse and found guilty in their absence. One man’s ill health cannot be a barrier to the greater public interest.”

The letter was also co-signed by Labour’s John Mann, John Hemming and Tessa Munt of the Liberal Democrats, Tory Sarah Wollastoon, Naomi Long of the Alliance Party and Jim Shannon of the DUP.

Earlier Leicestershire Police, which has led the latest investigation against the peer, said it was “considering” contacting the Lords about an official letter Lord Janner signed on April 9 asking for a leave of absence.

The force also revealed that a number of new alleged victims have come forward to the Operaton Enamel police probe since it was revealed that Lord Janner would not be charged.

The CPS admitted last week there was enough evidence to prosecute the peer for 22 sex offences against nine people.

More than a dozen people came forward to claim he abused them during the 1960s, 1970s and 1980s, prosecutors said.

Greville Janner, the former Leicester West MP was originally investigated under three different police inquiries between 1991 and 2007 but never charged.

He was diagnosed with Alzheimer’s disease in 2009 and requires round-the-clock care.

The Labour Party said Lord Janner has been suspended in “light of these very serious allegations” but his family has repeatedly denied he is connected to any wrongdoing.

Boris Johnson said he would like to see a trial of facts, with a second opinion required on Lord Janner’s ability to stand trial.

The mayor of London, who is also standing as a Conservative parliamentary candidate, told his LBC Radio phone-in: “I think it’s very important that nobody should be under any impression Greville Janner has had an easy ride from the CPS or has been in some way allowed to escape justice.

“I have some sympathy with the DPP because, as I understand it, they are trying to cope with the fact Lord Janner has dementia and they can’t see how he could be put on trial.”

He added: “Yes, I think it’s obviously very, very disgraceful, it’s regrettable and questions need to be asked and there needs to be a proper analysis, if not an inquiry, into how we’ve managed to get to this position.

“It may be that there is a way forward. It may be that Alison Saunders can think of some approach that would allow the facts of the case to be tested in some legal way without, as it were, putting Lord Janner on trial.”

Told this was called a trial of facts, Mr Johnson said: “I think that would be good.

“I also think it might be reasonable for people to be satisfied, doubly sure, that the medical disqualification … is actually valid. I think we might need a second opinion from the doctors, as it were.”