The CPS announced that Janner will not face charges over child sex abuse allegations.

Lord Janner

Police in Scotland are investigating a historic abuse complaint against former Leicester MP and Labour peer Lord Janner.

The investigation relates to claims that Lord Janner took a boy north of the border in the 1970s and sexually assaulted him.

Police Scotland said officers are carrying out an inquiry into a historic complaint.

Lord Janner was Labour MP for the same seat for 27 years – Leicester North West from 1970-74, and Leicester West from 1974-97.

Detective Chief Superintendent Lesley Boal said: “Police Scotland is conducting an investigation into an historic complaint and, as such, it would be inappropriate to comment.

“Police Scotland is absolutely committed to preventing all forms of child abuse and to keeping children safe, while bringing perpetrators of abuse to justice, regardless of the passage of time.”

The Daily Mail said the alleged victim made a report at a police station in Edinburgh in 1991.

A Crown Office spokesman said: “We have not received a report in relation to this matter.”

Last month the Crown Prosecution Service, covering England and Wales, said it would review its decision not to charge Lord Janner over allegations of historic child sex abuse.

He was accused of a string of allegations during the 1960s, 1970s and 1980s but was deemed unfit to stand trial because he is suffering from dementia.

Justice Lowell Goddard, the New Zealand judge leading an independent inquiry into child sex abuse, said she would investigate claims against Lord Janner, and could even call him to give evidence.

He has denied the previous allegations against him.

The peer – who has been on a formal leave of absence from the upper house since October – was a Labour MP for 27 years from 1970, representing the same Leicester seat which had been held for the party by his father for the previous two decades.

He never served as a minister but sat on a series of influential parliamentary committees, chairing the employment committee between 1992 and 1996 and was made a life peer by Tony Blair after the 1997 general election Labour landslide.

He ran into controversy when Tories claimed he had a “conflict of interest” with employment committee inquiries into pay for privatised utility “fat cats” because he sat on the remuneration committee of Ladbroke’s.

A former president of the Board of Deputies of British Jews who has been active in efforts to get compensation for Holocaust victims, he claims to speak nine languages and is a member of the Magic Circle and the International Brotherhood of Magicians.

He will remain a member of the House of Lords until his death or until he formally retires under reforms passed last year.

But the peer, who has been suspended from the Labour Party, has not checked into the Parliamentary estate since December 2013 when he claimed expenses for 12 days’ work.