Richard John Bingham, 7th Earl of Lucan

Lucan was a well-known figure in high society. His whereabouts have been unknown since 1974, when his children's nanny, Sandra Rivett, was found murdered. Lady Lucan claimed that her husband had confessed to killing the woman, and, at the inquest, the coroner's jury brought in a verdict of unlawful killing, naming Lord Lucan as the murderer. Many alleged sightings of him have been reported since then, but the police investigation has drawn a total blank in its efforts to find the runaway earl.

Consequently, to "do a Lord Lucan" is to disappear or go missing. The phrase is generally applied in a humorous context.