The charismatic aristocrat, who disappeared hours after 29-year-old Sandra Rivett’s body was found at his central London home, was finally declared dead in 1999.
But there have long been claims that the debt-racked gambler was spirited away by his high-rolling friends and even watched his three children grow up in South Africa.
And doubts have persisted over his guilt, despite his wife, Lady Lucan, insisting that she was also attack by her estranged husband, who is the subject of a new ITV drama.
Their youngest daughter, barrister Lady Camilla Bloch QC, 43, recently broke her 39-year silence to say there was no proof that her father was a murderer.
However, an inquest, seven months after Lord Lucan’s disappearance, named him as Miss Rivett’s murderer – the last time coroner’s court was allowed to do so.
Police believe he planned to kill his wife in the basement of the Belgravia home they had shared until their marriage collapsed and she won custody of the children in 1972.
But the apparent ambush failed on the night of November 7, 1974, after the women who entered the cellar was instead Miss Rivett, who had a seven-year-old son.
Using the same bandaged lead pipe, he is then said to have attacked Lady Lucan, who fled in a blood-soaked nightdress to a nearby pub and shrieked: “Murder, murder! I think my neck has been broken! He’s tried to kill me.”
Police rushed to the house and found a body and a blood-stained lead piping. The three children – Frances, who was then ten, George, seven, and Camilla, four – were safe.
Shortly after midnight, they then broke into the property 100 yards away where Lord Lucan had been living - but he was not there.
The professional gambler had driven a borrowed Ford Corsair 42 miles to meet Susan Maxwell-Scott at her home in Uckfield, East Sussex, which was his last confirmed sighting.
He asked her to post two letters, in which he wrote in one that he had entered the house after seeing his wife struggling with an assailant.
The Corsair was found 16 miles away with lead pipe and a bottle of vodka in the boot.
The aristocrat - who was born Richard Bingham and later became the 7th Earl of Lucan, although preferred the title Lord – has not been seen since.
Police believe he probably drowned, but a sea search found no evidence of this.
Indeed, it was not until 1999 – after his son George had been denied the inheritance of the peer’s seat in the House of Lords – that a court finally declared him legally dead.
However, Lord Lucan’s brother, Hugh Bingham, is said to have told the BBC off-camera that the earl died in 2004 and is buried in Africa, the Mail On Sunday reported in February this year.
Lord Lucan’s children were packed off to South Africa after the murder and it has even been claimed that their father watched them from a distance.
But amid this renewed speculation, George Bingham claims his father took his life by downing sleeping pills and whisky on a boat in the channel.
Others believe the fugitive is still alive. If so, he would be 74 years old.
Whatever the truth concerning his disappearance, it is certainly the case that Lord Lucan lived an intriguing life.
After his birth in 1934, his parents had limited involvement in his upbringing since he was initially cared for by a nursery maid due to his mother’s serious illness.
And, when World War II began when he was just four, he was sent to America, where he lived a life of opulence with wealthy family friends.
In 1945, he returned to austerity Britain and was sent to Eton, where he developed his love of gambling by regularly playing truant so that he could go to horse races.
During his National Service he spent three years in his father’s army regiment, the Coldstream Guards, in Germany, where he learned poker.
But his betting habit and expensive tastes really burgeoned when he took a high-paid job as a merchant banker in the City of London in 1955.
He left that job in 1960 and became a professional gambler.
The period saw him become one of the most charismatic and best-known figures in British high society.
He drove an Aston Martin and was even considered for an on-screen role as the first James Bond.
He also raced powerboats – with British Pathé footage from 1964 showing Lucky, as Lord Lucan was known to friends, in the No 49 craft during the Cowes to Torquay challenge.
But it was this opulent lifestyle and gambling debts – including a loss of £50,000 in one month - that would ultimately lead to his downfall.
Although, none of this – and perhaps nothing ever will – explain how he fled justice and what really happened to him.