Media playback is unsupported on your device Media caption Lord Lucan's brother 'encouraged by idea that there is fresh evidence'

A written statement from Lord Lucan's sister suggesting another man was at his house around the time of the murder of the family nanny has been uncovered.

Lady Sarah Gibbs told police at the time the Lucans' young daughters talked about a "boyfriend" at the home, BBC Inside Out has learned.

The 7th Earl of Lucan vanished after the death of Sandra Rivett in 1974 and an inquest found that he murdered her.

His brother Hugh Bingham has called for the evidence to be looked at afresh.

In the statement from November 1974, Lady Sarah said her four-year-old niece Lady Camilla Bingham told of a mystery man who sometimes slept in "nanny's room and nanny sleeps with us" and sometimes slept in "mummy's - she's got a gigantic bed".

Lady Sarah, who died in 2001, said in the statement: "We were talking about home, that is 46 Lower Belgrave Street and Camilla said the boyfriend always stays upstairs while we have lunch until we ring the buzzer.

LORD LUCAN MYSTERY 7 November 1974 - Sandra Rivett, the nanny of Lord Lucan's children, is found murdered

8 November 1974 - Lord Lucan disappears and his car is found abandoned at the port of Newhaven, East Sussex, prompting an international search

19 June 1975 - An inquest jury decides Lord Lucan murdered Mrs Rivett

October 1999 - Lord Lucan is declared officially dead by the High Court

Since his disappearance there have been dozens of alleged sightings of the peer in countries around the world

"I said to her 'What's his name?'. She said 'I don't know, he hasn't told me his name'.

"I said 'Where does he live?'. She said 'He lives in the house with us'."

When asked whether the man was the boyfriend of Lady Lucan or the nanny, Lady Sarah said: "I wouldn't know, I'm assuming she meant the nanny because Frances [10-year-old Lady Frances Bingham] referred to the boyfriend when I told her that the nanny was dead."

Lord Lucan claimed later in a letter that on the night of the murder he witnessed a man fighting with his estranged wife Lady Lucan in the basement of the family home but the man fled.

Speaking from his home in Johannesburg, South Africa, Mr Bingham told BBC Inside Out South East he was annoyed the witness statement was not presented at the 1975 inquest into Mrs Rivett's death.

'Result set aside'

The jury found that Lord Lucan had murdered the nanny.

Mr Bingham added: "It is certainly the first time that I've heard of a second man established in the house.

Image caption Lord Lucan's brother Hugh Bingham has called for the evidence the BBC uncovered to be investigated

"I'm encouraged by the idea that there is a fresh source of evidence and that I feel wants to be given a fair hearing and this seems to me to be one way of achieving that.

"Let us hope that now with the way in which the evidence seems to be gathering, there is a chance that maybe the inquest result could be set aside.

"If that happened then the warrant of arrest would fall away and my brother's situation would be restored to the normal situation of a man innocent until proven guilty."

Neil Berriman, who discovered in 2004 that Mrs Rivett was his birth mother, has backed calls for the claims in the witness statement to be investigated.

If he never murdered my mother and if there is another murderer I need to get to the bottom of it Neil Berriman, Sandra Rivett's son

Mr Berriman, from Haslemere in Surrey, said: "As far as I'm concerned, he [Lord Lucan] murdered my mother - and if he never murdered my mother and if there is another murderer I need to get to the bottom of it."

Retired Det Sgt Graham Forsyth, who witnessed Lady Sarah's statement, told Inside Out he believed Mrs Rivett may have had a boyfriend who stayed over at the house.

He did not think the man was traced because the police believed Lord Lucan was the murderer "as was subsequently found at the inquest".

Lord Lucan's estranged wife Lady Lucan has not commented on the witness statement.

The new evidence came to light after BBC Inside Out South East was handed three boxes of notebooks, diaries, tapes and address books found by the daughter of the late Det Ch Insp David Gerring, a key detective in the Lucan case.

The documents also reveal that police believed Lucan may have visited a Scottish estate in the late 1970s and could have been in Mozambique up to 2002.

Lord Lucan, born Richard John Bingham in 1934, has not been seen since the day after Sandra Rivett was found murdered.

His car was later found abandoned in Newhaven, East Sussex.

The peer was officially declared dead by the High Court in 1999.

Since his disappearance at the age of 39 there have been more than 70 reported sightings of him in countries across the world including South Africa, Australia, Ireland and the Netherlands.

Inside Out is broadcast on BBC One South East, South and London on Monday, 10 December at 19:30 GMT. It is also available nationwide on the BBC iPlayer for seven days thereafter.