Speaking for the first time about his father’s mysterious disappearance 38 years ago he said he was certain “Dad felt backed into a terrible corner’ and wished to “vanish for ever.”

He has insisted he was certain his father was not the killer of family nanny Ms Rivett, 29, who was found bludgeoned to death in the home of Lord Lucan’s estranged wife. The attacker then turned on Lady Lucan, beating her severely before she managed to escape.

Lord Lucan’s car was later found abandoned and soaked in blood in Newhaven, East Sussex, and an inquest jury declared him the killer a year later.

Bingham said, however: “I’ve always thought it extraordinarily unlikely my father went into our family home, wandered down and killed anybody with a piece of lead piping for the love of his children, while those very children might well have come downstairs and witnessed this appalling carnage.”

He said his father had a huge sense of pride and would have been unable to cope with being accused of the murder. “He would have got on board with a bottle of whisky and some pills and taken it out to the 50 metre mark, the point where if you go down you’re not going to come back up again, but not so far out that you are in the shipping lane.”

Following Lucan’s disappearance, there were reported sightings of him in Australia, Ireland and South Africa. His brother Hugh Bingham said he was confident Lucan escaped the UK to begin a new life on the African continent.

The former merchant banker has said he would prefer that to trying to understand why his father had left the family for “no apparent reason”.