Scotland Yard detectives are looking into allegations that senior politicians abused children in the 1980s and escaped justice because they were protected by their powerful connections.
During past weeks officers from the Metropolitan Police’s child abuse investigation team have interviewed several adults who claim that they were sexually assaulted as children by MPs in a paedophile ring.
The team was set up following claims by Labour MP Tom Watson in the House Commons that the police should look afresh at claims of a “powerful paedophile network linked to Parliament and No 10”.
Until today when the Metropolitan Police confirmed its existence, the inquiry, Operation Fairbank, had been operating in secret at the headquarters of the Child Abuse Investigation Team at Empress State Building in Earl’s Court, London.
Officers with the team, part of the Specialist Crimes and Operations Directorate, have spoken regularly to Mr Watson.
The Metropolitan Police stressed that Operation Fairbank was a “scoping exercise” aimed at a preliminary assessment of the evidence rather than a formal inquiry.
However, officers are understood to be taking the witnesses’s claims very seriously and are expected to make arrests in coming weeks.
Raising the issue at Prime Minister’s Questions on 24 October, Mr Watson - who alleged widespread phone hacking at the News of the World before police began a new inquiry - urged police to re-open the evidence file on Peter Righton.
Righton, a former consultant to the National Children’s Bureau, was convicted of importing and possessing illegal homosexual pornographic material in 1992.
Saying that the file contained “clear intelligence of a widespread paedophile ring”, the MP said: “One of its members boasts of a link to a senior aide of a former Prime Minister, who says he could smuggle indecent images of children from abroad.
“The leads were not followed up, but if the files still exist, I want to ensure that the Metropolitan Police secure the evidence, re-examine it, and investigate clear intelligence suggesting a powerful paedophile network linked to Parliament and No 10.”
Five officers are working on the inquiry.
In a statement, the Metropolitan Police said: “Officers have spoken with MP Tom Watson who has passed on some information which is now being looked into.
“As a result, officers are continuing to collate information. This is being assessed by officers under Operation Fairbank.
“We would continue to appeal to anyone who has concerns to report them to us. Any information is treated with the utmost seriousness and can be given in confidence.”
Updating the public on the investigation into alleged sexual offences in showbusiness, Scotland Yard said that the number of alleged sex abuse victims of the late BBC TV presenter Jimmy Savile had reached 450.
Commander Peter Spindler, head of Operation Yewtree, suggested Savile - who escaped detection and died aged 84 last October - had been a serial abuser of children.
Commander Spindler said: "Savile's offending peaked in the 70s and what we can show, or will be showing in the New Year, is how he used his position in society across the country - the crimes relate to 17 different police force areas - how he exploited this position to get his sexual gratification."
In total, 589 alleged victims have come forward to allege abuse by Savile and others.
Over the past two months, detectives have arrested several high-profile names, including the comedian Freddie Starr, the former BBC disc jockey Dave Lee Travis, the former BBC producer Wilfred De'Ath and the publicist Max Clifford. They all deny any wrongdoing. Gary Glitter, who was also arrested, has not yet issued a statement.