London - Lady Lucan, a British aristocrat who survived a vicious 1974 attack by her husband that sparked a decades-long mystery, has died. She was 80.London's Metropolitan Police said officers were called to a house in the upscale Belgravia neighborhood "and found an 80-year-old woman unresponsive"."Although we await formal identification we are confident that the deceased is Lady Lucan," whose name is Veronica Bingham, the force said.Police said on Wednesday that the death is being treated as unexplained but not suspicious.Her husband, John Bingham, the 7th Earl of Lucan, vanished after the body of nanny Sandra Rivett was found at the family's London home on November 7, 1974. Lady Lucan was bludgeoned when she ran downstairs to investigate, but managed to escape and raise the alarm.Lord Lucan's bloodstained car was later found abandoned near England's south coast, but he was never successfully traced.Lucan was never seen in public again, and his body was never found, leading to decades of fevered speculation about his whereabouts.'Grimly unhappy'In 1975, an inquest jury declared him to have been Rivett's killer. Detectives believe the aristocrat - an abusive husband and heavy gambler nicknamed "Lucky Lucan" - intended to murder his wife and killed the nanny by mistake.His marriage to Lady Lucan had been described as "grimly unhappy".The mystery of Lord Lucan's disappearance still intrigues Britain. The High Court declared him dead for probate purposes in 1999, but there have been scores of reported sightings around the world, in countries including Australia, Ireland, South Africa and New Zealand.In a television documentary earlier this year, Lady Lucan said she believed Lord Lucan had jumped off a ferry shortly after the killing."I would say he got on the ferry and jumped off in the middle of the Channel in the way of the propellers so that his remains wouldn't be found," she said, calling what she believed to be his final act "brave".The couple had three children.A British court last year issued a "presumption of death" certificate for Lord Lucan, a ruling that cleared the way for the couple's son, George Bingham, to become the 8th Earl of Lucan.