Michael Fox (87), his wife, Veronica (85), and their son, Paul (55), watched from their home in Grouville as their great-niece Jessica Fox claimed gold for Australia in the C1 canoe slalom.
Speaking following her success, Michael said he was very proud of his great niece who also won a bronze medal earlier in the week in the K1 kayak event.
The difference between a canoe and kayak slalom lies in the paddle used, with the canoe events using a single-bladed paddle and the kayaks featuring a double-bladed version.
Jessica comes from a sporting family, as her parents, Richard and Myriam, are both former world canoe champions.
The French-born Olympian was the fastest qualifier for the final in both the K1 and C1 before picking up bronze and gold medals respectively.
Commenting on her achievements, Michael said: ‘We saw the competition live on TV this morning. It was very exciting. We were interested to see that the British girl [Mallory Franklin] did a very fast time and wondered if Jess would pull out all the stops and do a faster one.
‘I’m pleased to say she did not let us down. We had a gold medal for the Foxes and a silver medal for the Brits, which is very satisfying.
‘It has been a successful Olympics for Jess, winning bronze in the kayak slalom and then topping it off with a gold in the canoe slalom. It’s something to be very proud of,’ he added.
Earlier this week, Sark resident Carl Hester won a bronze medal in the dressage on his horse, En Vogue. He obtained a score of 2577.5 to put Team GB into second place after the first round.
It is Mr Hester’s third Olympic medal. He won gold in 2012 and silver in 2016.