The family of a missing boy have been told by police that he may have been abducted, abused and murdered by a paedophile ring of leading establishment figures.

Martin Allen, the son of the chauffeur of a Australian high commissioner, went missing aged 15 from King's Cross on his way to home in Kensington in November 1979.

His brother Kevin, 51, has said he was called by Detective Chief Inspector Diane Tudway of the Metropolitan Police on Friday, who told him she was investigating whether Martin’s disappearance is linked to an alleged ring made up of MPs and senior figures of authority.

Operation Midland, the investigation into the deaths, was set up this month and officers said that Operation Fairbank intelligence has led them to look into whether high-profile officials were involved in organised child sex abuse and murder in the 1970s and 1980s at locations including the Elm Guest House in Barnes, southwest London.

A man only known as Nick, who is in his 40s, claims he was raped by a former Conservative MP and alleges that he saw three boys being murdered. He said one was deliberately run over, a second was strangled by a Conservative MP and the third was killed in front of a government minister. All of the boys were aged between 10 and 14, Nick said.

He had said: “We were asked if we wanted a drink. It was always whisky. Both MPs were brutal. I was raped over a bath-tub while my head was beneath the water.”

The case of Martin Allen’s disappearance was closed in the 1980s, but reopened in 2009 and shut again last year. Mr Allen and his brother, Jeffrey, 61, said that police claimed in 2009 that files has been destroyed by a flood.

“We had to give evidence over again to the police,” Mr Allen said. “But then later, when the case was still open, the two detectives on it told us that a retired police officer had withdrawn the files and gone to Spain.

“They said they had tried to get a warrant to question the officer but couldn’t get it from the Spanish authorities. You don’t know what to believe.”

Jeffrey Allen said the detective who led the case in 1979 had told his family that there were “high-up people involved” and that they should stop talking and “not take it further because someone will get hurt”.

Kevin Allen told the Mirror: “I’ve no faith in the police. They failed us.

“Within a couple of months of Martin disappearing, my ­father and I said, ‘There’s something not right here.’ Police weren’t doing enough. They went through the motions.

“So it didn’t surprise me when a senior officer warned me I could get hurt. I’ve always said there was something, Establishment involvement, in Martin’s disappearance.”

The Met said it could not comment on the allegations.

Last week Vishambar Mehrotra, an ex-magistrate and father of Vishal, eight, who was murdered in 1981, said he was called by a male prostitute who claimed that the boy had been taken to the guest house to be abused.