A man told police a false “extraordinary tale” of child sexual abuse and murder by public figures, a court has heard.
Carl Beech, 51, made claims about “three child murders, multiple rapes, kidnapping, false imprisonment and widespread sexual abuse”.
Those accused included Lord Brittan, Lord Bramall, and ex-MP Harvey Proctor.
Mr Beech denies 12 counts of perverting the course of justice and one of fraud.
Mr Beech, formerly from Gloucester and known as “Nick” when he made the claims, was in Newcastle Crown Court on Tuesday as prosecutor Tony Badenoch QC said: “This case concerns the making of false allegations of the most serious kind”.
He said the case also relates to claims made “against a showbusiness personality” who he named as Jimmy Savile.
Mr Beech “claimed that he was the victim of much of the abuse and he was a direct witness to the killing of three young boys”, jurors heard.
The allegations concerned young boys, and the prosecutor said: “It is quite impossible to conceive of allegations of a worse kind to be made.”
“Immeasurable distress” had been caused to those accused and those close to them and they had suffered “obvious reputational damage”, said the prosecutor.
Mr Proctor has spoken freely in public to defend himself from the charge that “he is a sadistic child killer and that he committed other serious sexual offences”, the court heard.
Jurors were told that, as an entirely innocent man, Mr Proctor is “still enraged”.
He and Lord Bramall had their homes searched as a result of the allegations.
Lord Bramall’s wife died during the police inquiry – codenamed Operation Midland – and Lord Brittan died while under investigation.
Mr Beech claimed that one of the boys he witnessed being murdered was Martin Allen, a 15-year-old boy who went missing in London in 1979 and has not been seen since, jurors heard.
Martin Allen’s brother Kevin was contacted by Scotland Yard in 2014 and told his brother may have been linked to a VIP paedophile ring.
Mr Badenoch said: “The source of that false hope to Kevin Allen, thirty five years after his brother went missing, was ultimately the false allegations of this defendant, Carl Beech.”
The court heard that the Metropolitan Police spent £2m investigating the claims and described them publicly as “credible and true”.
In 2016, when the investigation ended with no further action being taken, the Met asked Northumbria Police to investigate the accuser himself.
“Carl Beech’s own words were at the centre of their investigation and are now at the core of this case,” Mr Badenoch said.
Police searched Mr Beech’s Gloucester home in November 2016 and seized several electronic devices.
During their investigation, a number of Mr Beech’s claims “were found to be provably false”.
“He had lied about the content of these allegations, taken active steps to embellish a false story, and then cover his tracks when challenged,” Mr Badenoch said.
When questioned by police about this, he “fled the country and lived overseas as a fugitive” before being located in Sweden.
The trial continues.