The eldest son of broadcaster David Frost has died at the age of 31. Miles Frost collapsed while out jogging at the family's home in Oxfordshire on Sunday, his Godfather said.
Friends said the financial investor had appeared "in great form" in recent weeks and there was no indication of any health problems.
David (inset below) died two years ago, aged 74, after suffering a heart attack on the Queen Elizabeth cruise ship.
Michael Rosenberg, David's former business partner and Godfather to Miles, said the family were "totally in shock" by his sudden death.
SHOCK
Lord Chadlington, a friend of the Frost family, said: "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 sign that anything was wrong.
"The Frost family are extremely close and they will all miss him terribly, as we all will. It is hard to lose a loved one at any age, but 31 really is difficult to comprehend."
David Frost was a television star for more than 50 years and was known for his incisive interviews - most famously with disgraced US president Richard Nixon.