21/07/2015 05:13 BST | Updated 21/07/2015 07:59 BST

Sir David Frost's Son, Miles, Dies While Out On A Run, Aged 31

Sir David Frost’s family are grieving the loss of the late broadcaster’s son, after 31-year-old Miles Frost died while out jogging.

Miles - the eldest of David’s three children with wife Lady Carina Fitzalan-Howard - collapsed during a run near the family’s holiday home in Oxfordshire on Sunday (19 July).

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Miles Frost with late father David in 2012

The financier was a keen athlete, and family friend, Lord Chadlington, said that Miles had showed no signs of any health problems.

Speaking about his death to the Daily Mail, he 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 signs that anything was wrong. It just underscores the fragility of life.

“There will be a post mortem examination but all we know is that he collapsed while jogging.”

He added: “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.”

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Miles (second from left) with his brothers and mother at David's funeral

Miles had previously completed a half marathon in the Lewa Game Reserve in Kenya, which is one of the most gruelling due to the altitude and heat.

He is survived by younger brothers Wilfred, 29, and George, 28, and mother Lady Carina Fitzalan-Howard.

Sir David died of a heart attack two years ago aged 74, while aboard the Queen Elizabeth II cruise liner.

Photo gallery Sir David Frost Memorial Service See Gallery