The son of the nanny murdered by Lord Lucan is to publish private diaries and papers of a senior policeman who worked on the ­investigation, in his hunt for justice.

Neil Berriman, whose mum Sandra Rivett was battered to death in 1974, will put the information on a website, as he continues to press Scotland Yard to arrest an elderly Englishman in Australia he claims is the fugitive peer.

The 53-year-old has been given access to the secret memoirs of former Det Chief Insp David “Buster” Gerring, who believed Lord Lucan fled abroad after the murder and did not kill himself.

Builder Mr Berriman also hopes the website, lordlucanthetruth.com, will help other victims of unsolved crimes.

He said: “The daughter of David Gerring, the original Scotland Yard detective in charge of my mother’s murder, passed me her late father’s police records, diaries and papers.

Sandra Rivett was murdered in 1974

“Chief Inspector Gerring always insisted Lucan escaped abroad.

“Statement by statement, record by record, I will put his and other Lucan case files up on the website so they can be scrutinised by all.

“I’ve compiled dozens of witness statements, collected hundreds of ­original Scotland Yard documents, confidential reports and evidence from people, who like me, all believe Lucan escaped abroad.

Neil Berriman (pictured), son of Sandra Rivett

"Now the time has come to join the dots and present the whole picture behind Britain’s biggest unsolved murder and missing person case.

“I want us to help them, to gather fresh information that may help ­kick-start cold cases. Nine months since handing over my evidence to Scotland Yard, their official line is, that the man remains a suspect and the Lucan case is open and being investigated.”

Sandra was killed in Belgravia, West London, aged 29. It is believed Lord Lucan mistook her for his wife, Veronica, who was divorcing him in a bitter split.

Detective Chief Inspector David Gerring and Chief Superintendent Roy Ranson

Some claim the 39-year-old peer killed himself by jumping from a ­cross-channel ferry. No body was found.

Mr Gerring’s daughter Davina ­Chambers said: “My dad always believed Lucan was alive. He died in 2004 and I knew there was a box of his papers in the loft.

"I found lots of items in ­connection with the Lucan case. I have now given Neil access to them.”

Mr Berriman, of Milland, West Sussex, said he hopes his website will ­“champion other historical criminal cases that have fallen by the wayside, left in forgotten police store cupboards”.

He added: “The name Lord Lucan has been etched in history, the name of the young woman he murdered is almost forgotten.”