The medical notes of Lord Lucan which show that he had surgery on his nose prior to his disappearance have sold at auction for £100.
The record contains details of the visit that he made to a hospital after he broke his nose in a speedboat accident in 1963.
His cousin Victor Bingham said the notes could be valuable for any investigation into the lord's disappearance.
He said: "If they ever find the body, that would be a very important clue to help identify him."
The medical note, made by Dr John Watson of Harley Street, sold at Duke's Auctioneers, in Dorchester, Dorset, for £100 plus buyer's premium of 19.5% and VAT.
The 7th Earl of Lucan, who was 28 at the time of the accident, remained in hospital for three days and returned for the splint and sutures to be removed.
Lord Lucan, whose real name was Richard John Bingham, disappeared in 1974 after his children's nanny was found dead in Belgravia, London.