The 10th Earl of Shaftesbury has disappeared on holiday in France, sparking a police hunt on both sides of the Channel.
The Earl has not contacted family or friends since 5 November
The 66-year-old, whose full name is Anthony Ashley-Cooper, has not been seen since 5 November and was due to return to the UK on 10 November.
He had been staying in the Antibes area of France.
Police in Nice are leading the investigation with help from police in London and Sussex, where he has homes.
The Earl, who has been married three times and has two sons, has homes in England in Hove and in the City of London.
'A little extraordinary'
French Police said he arrived in Nice, on France's Mediterranean coast, by plane on 3 November.
He is known to have contacted family and friends on 4 and 5 November but has not been in touch since.
Police in Nice said the Earl has a girlfriend in the nearby town of Grasse.
A spokesman said: "We think he did not take an airplane to go to another town.
"Yesterday, in a French newspaper, we put his photograph but we have no news."
The spokesman said the Earl was "a little extraordinary" in that he could get on a plane to another country without telling anyone where he was going.
The report in the newspaper Nice Matin said the Earl's lawyer had told police he had been involved in a confrontation in Grasse last year and his disappearance had been reported by a female friend.
Sussex Police said they had been in regular contact with the Earl's eldest son, also called Anthony, who is at the family seat in Wimborne, Dorset.
They said the Earl has a mobile phone but his family have been unable to get through.
The Earl is described as white, with a pale but possibly tanned complexion.
He is 6ft 1in tall and thin, with thinning grey hair and blue eyes, and sometimes wears large heavy-framed red and pink glasses.
Police said he normally wears casual clothing and a large watch.
He inherited his title as the 10th Earl of Shaftesbury from his grandfather at the age of 22.