Sir David Frost’s eldest son Miles has died aged 31 after collapsing during a jog.
Friends said the financial investor was at the grounds of his family home in Oxfordshire when he fell ill.
Lord Chadlington, a family friend, said there had been no indications of any health problems. He told the Daily Mail: “Miles was a wonderful eldest son who was very well loved by all his friends and family. This is a terrible shock.
“I had breakfast with him last Thursday and he was in great form. There was no signs that anything was wrong.”
Eton-educated Miles co-founded the investment firm Frost Brooks. He worked at the private equity firm LDC for five years prior to this.
He also ran a half-marathon in the Lewa Game Reserve in Kenya in 2013.
A post mortem is expected to take place to determine the cause of his death.
A spokeswoman from South Central Ambulance Service NHS Foundation Trust said: “We were called at 14.33pm on 19 July to a medical emergency in the Nuffield area, Oxfordshire.
“We sent the Hampshire and Isle of Wight Air Ambulance, an ambulance crew and an ambulance officer to the scene.
“Sadly, one patient, an adult male, was confirmed deceased at scene.”
His father Sir David died of a heart attack two years ago aged 74 on the Queen Elizabeth cruise ship where he was giving a speech.
The veteran BBC broadcaster was known for his revealing interviews with figures including the former US president Richard Nixon, Margaret Thatcher, Orson Welles, Tennessee Williams and The Beatles.Reuse content