Lord Janner's son has vowed to bring a private prosecution against the man at the centre of Westminster child abuse claims, who has himself been charged with paedophile offences.
The accuser, who has only been named as "Nick", sparked Operation Midland after he told police he had been raped and abused for nine years by the VIP gang.
But the £2.5 million investigation collapsed without any arrests and Nick has appeared in court charged with possession of indecent images of children, the Sun and Daily Mail reported.
His court appearance months ago can be reported for the first time after a legal challenge by the papers.
Last September, Northumbria Police said it had passed a file to the Crown Prosecution Service (CPS) to decide if charges of perverting the course of justice and fraud would be brought against him.
Labour peer and former MP Lord Janner was among those accused and died in 2015 before his name was cleared.
His son Daniel Janner QC has blasted the CPS for the delay in making a decision on charging Nick.
"Nick accused my late father of raping him - he must now be prosecuted for his lies," he said.
"If the CPS refuse, I will bring a private prosecution.
"The child abuse enquiry must now drop the strand in my innocent late father's name, all the civil abuse claims against him having been dropped."
Nick said in an interview with police in September 2016 that he was driven to various addresses in London and introduced to people at parties.
"He associated Lord Janner with the group who physically and sexually assaulted and raped him," Mr Janner said.
"I'm concerned, my father was named by Nick so I'm going to prosecute him if the CPS don't.
"This delay is totally wrong, it's extraordinary and smacks of a cover up."
Former MP Harvey Proctor, who was also the subject of Nick's disproved allegations, has called for an independent inquiry into the anonymity given to sex abuse victims.
"I have now come to the conclusion that the whole question of anonymity needs a complete review, investigation and overhaul," he said.
"I believe the Home Secretary, if not the Prime Minister, should set up an independent inquiry into the issue of anonymity.
"We can't rely upon the police to police themselves on this matter."
The Metropolitan Police raided the homes of prominent figures, including Lord Bramall and the late ex-home secretary Lord Brittan, despite the case relying solely on the claims of Nick.
He now faces six charges, including making indecent images of children, all of which he has denied.
A Crown Prosecution Service (CPS) spokesman said: "In June 2017 a man was charged with four counts of making indecent images of children, one count of possessing indecent images of children and one count of voyeurism.
"The man has pleaded not guilty to all charges and the matter is due for trial before the Crown Court."