Lady Lucan was found dead on Monday at her home in Belgravia where her husband Lord Lucan famously vanished 43 years ago after bludgeoning their nanny to death.
The 80-year-old aristocrat was reported missing by a friend yesterday afternoon after she failed to appear in Green Park, where she walked every day at the same time.
Police battered down the door of her mews house in central London to find Veronica, the Dowager Countess of Lucan, dead.
Her death was being treated as unexplained, with police still trying to establish the circumstances.
Her son George, who took his father’s title last year, confirmed his mother’s death.
Speaking on Tuesday, he said: “She passed away yesterday at home, alone and apparently peacefully.
“Police were alerted by a companion to a three-day absence and made entry today.”
Lady Lucan was one of the last people to see her husband John Bingham, the 7th Earl of Lucan, alive before he disappeared on the night of November 7, 1974, after bludgeoning to death Sandra Rivett, their children’s nanny, in the mistaken belief that she was his wife.
The countess was in the house watching TV in her bedroom that night when the 29-year-old nanny was killed as she went downstairs to the unlit basement to make her employer a cup of tea.
The countess contends that she disturbed her husband after the fatal assault. He hit her four times with a length of bandaged metal piping before she managed to stop him.
Then, after she had persuaded her husband to get her a glass of water, she fled to a nearby pub and raised the alarm.
She recalled: “He told me, ‘I’ll go to Broadmoor for this’. Our children George and Camilla were seven and three when it happened, and asleep in bed.”
Lord Lucan fled the murder scene in a car he had borrowed. His body has never been found.
Over the years several fantastical theories about his disappearance have placed him in the Australian outback, as a hippy drop-out in Goa, and even fed to the tigers at his friend John Aspinall’s zoo.
Although a High Court judge granted a death certificate last year allowing his son to inherit his title, this has provided neither resolution nor a conclusion to the mystery.
Lady Lucan remained closer to the truth than anyone and with her death, the possibility of her husband’s disappearance being solved looks ever more remote. She believed that the note he left, with the poignant sentence, ‘Please tell those that you know, that all I cared about was them (the children)’, was proof her husband intended suicide.
That night he called at the home of friends in a Sussex village, before leaving in the early hours. Lucan told them he had happened on an attacker hitting his wife as he passed the family home.
His version of the story was that his wife had accused him of hiring a hitman to kill her and he claimed he was going to ‘lie doggo’ for a while.
Three days later his borrowed car was found abandoned and blood-splattered – with a section of bandaged lead piping in the boot – at the cross-Channel port of Newhaven, East Sussex.
There has been no concrete clue to his whereabouts since. If still alive today, he would be 82.
In an interview earlier this year, Lady Lucan said she believed that ‘he got on a ferry and jumped off mid-Channel, and was chopped up by the propeller – which is why his body was never found’.
She said that as a powerboat racer he had a detailed knowledge of propellers and would have known precisely where to jump so his remains were destroyed.
She had recently written a book about the mystery, telling of her joyless marriage to the professional gambler.
An inquest jury at a coroner’s court named Lord Lucan, in his absence, as the murderer of Mrs Rivett – making him the last person in Britain to be declared a murderer by an inquest jury, before the procedure was outlawed. He was never convicted in a criminal court.
Both his son George, a merchant banker, and younger daughter Camilla, a QC, had publicly made clear that their father should not be assumed culpable, to the fury of their mother.
Last night it was unclear whether all her family had been told of her death as they have been estranged for many years.
Her daughters Frances, 52, and Camilla, 47, and son George, 50, as well as her sister Christina Shand Kydd, who was distantly related by marriage to Princess Diana, have not been in contact with her for decades.
Lady Lucan had five grandchildren but never met any of them.
She lived alone in a two-bedroom mews cottage which was originally bought as a guest house during her ill-fated marriage to Lucan and provided a temporary home for her husband when they separated after he lost a bitter battle for custody of their children.
She moved into it three years after his disappearance.
It is just a stone’s throw from the five-storey family home in Lower Belgrave Street where the murder happened.
Earlier this year, she said: “I don’t fear dying alone – not at all. But I do fear dependency. I’d find that very depressing. It would be horrible to feel you were a burden.
“Your faculties start to fade when you reach 80, so I’ve been thinking about my death. I’d quite enjoy the rest of my life if I knew it was not going to end in something horrific. I’ve given it some thought and I support the idea of assisted suicide.”
She campaigned for assisted euthanasia and said she hoped to slip away peacefully before disease or dementia debilitate her.