THE eldest son of the late writer and broadcaster David Frost has died at the age of 31 after suffering a heart attack while out jogging at the weekend.

A keen athlete, Miles Frost is said by friends to have shown no signs of ill health before his collapse on Sunday evening near the family home in Oxfordshire.

Educated at Eton and the University of Newcastle, Mr Frost was a financier, starting his career in 2006 with Lloyds Development Capital. He went on to co-found Frost Brooks, a boutique private equity firm, in 2012, which last year completed a multimillion-pound investment in Parcel Monkey Group, an ecommerce service provider.

Mr Frost had enjoyed playing football, tennis and cricket, and had run a half-marathon at the Lewa Game Reserve in Kenya in 2013. He was said to have appeared at a charity cricket match two weeks ago, and recently socialised with friends.

Lord Chadlington, a friend of the Frost family, said last night: “He was on excellent form on Thursday, and he was fine over the weekend. He was a very fit 31-year-old. There was no sign of illness, and he ate well. He had a heart attack while he was out jogging near Lady Frost’s house in the country and was taken to hospital.

“He was a wonderful man — both David and Lady Carina were very proud of their children. He was a very good eldest son. He would have been an enormous success.”

Mr Frost’s death comes two years after the death from a heart attack of his father, a prolific TV presenter and writer best known for his role in the satirical show That Was The Week That Was and his series of interviews with Richard Nixon in 1977. Frost elicited admissions from the former president of the United States that supported the conclusion that he had obstructed the course of justice during the Watergate scandal.

Mr Frost, who had no spouse or children, is survived by his brothers, Wilfred, 29, and George, 28, and their mother, Lady Carina.