British sailor Giles Scott told his father he was “relieved” not to have given him a heart attack after he retained his Olympic title in the men’s Finn in dramatic fashion in Tokyo.

The 34-year-old had a nine-point lead going into the final medal race but had to play catch-up after a poor start and crossed the line in fourth, which was enough to keep him ahead of Hungary’s Zsombor Berecz in silver.

John Scott and his wife Ros, who were watching at the National Sailing Academy in their hometown of Weymouth, Dorset, spoke to their son via video call after his victory.

“He said: ‘I’m relieved to see I didn’t give you a heart attack’,” the 69-year-old told the PA news agency.

“I can honestly say it’s the most stressful race I’ve ever watched.

“He just pushed a little too hard at the start and we really were thinking: ‘Gosh, this is going to be tough…’ To battle back through that quality of field we knew would be a challenge – and he just did it.

“I’m proud for him as much I’m proud of him … he’s shown his mettle … and shown why he was defending Olympic champion.”

Mr Scott, the former head of UK Anti-Doping, said he was “up at 2.30am” because he could not sleep ahead of his son’s victory, which is Scott’s second and Britain’s sixth successive title in the Finn.

He was able to speak with his son on the slipway just after the event finished because his other son Nick is in Tokyo with the British Olympic Association – one of Scott’s two brothers who also sailed competitively and made the Olympic development squad.

“We put them in boats when we were living in Canada, I suppose Giles was three or four,” said Mr Scott.

“He’s always loved it and I think it helped that he had two brothers who also sailed so he was chasing his older brother… all three boys got into the Olympic development squad.

“We started them fairly young, but that was more for recreation – we’re not competitive sailors, my wife and I, we just loved the idea of them being out on the water.”

Mr Scott said his wife Ros managed to get his son into sailing lessons two years early, aged six instead of eight, in Canada.

Asked if there was ever a moment of doubt that his son would rise to the pinnacle of his sport, Mr Scott said: “I can honestly say no… he’s always been remarkably clear in his head about what he wants to do.

“But the one thing I’m most proud my son has is his modesty – he doesn’t take anything for granted and is very humble in his achievements.”

Scott missed out on competing at the London 2012 Olympics after triple champion Sir Ben Ainslie pipped him to selection for the Finn.

“That was tough for him in 2012, when he was sailing immensely well,” Mr Scott said.

“But he just got on with it and here we are with two gold medals – brilliant.”