Huntingdon's Giles Scott defended his Olympic finn sailing title in a thrilling medal race.
Scott had won six out of the 10 races in the qualifying regatta, leaving him needing a top-five finish in final race to secure gold.
Around the final mark his closest rival, Hungary's Zsombor Bereca was surging clear and Scott had work to do seventh.
However, he managed to inch himself through the fleet, crossing the line in fourth by a fraction to follow up his win at Rio in 2016.
British success in the heavyweight title now stretches six straight Games back to 2000, with Iain Percy's Sydney success followed up a hat-trick of titles for Sir Ben Ainslie in 2004, 2008 and 2012.
It was a second gold for the British sailing of the day in Enoshima, coming just 57 minutes after Stuart Bithell and Dylan Fletcher won the men's 49er class.
Scott, who learned to sail on Grafham Water, said: “I made it by the skin of my teeth, it was properly down to the wire, it was really tight. I tried to stay relaxed but I've never been involved in a boat race as close as that.
“It was mine to lose, if it had been any other race there was no way I'd go back.
“It's special. Since the America's Cup I've been sailing for three and a bit months, I was second at the Europeans and ninth at the Worlds but the target was the Olympics. We've had a few wobbles along the way but we've done it when we needed to.
“It's been a funny old year for everyone, I'm just pretty stoked.
“That's the greatest pressure of my career. It climbed throughout the race, that was full on.
"Sailing is so dependent on the wind, when the wind is in it's super exciting but in light conditions like that it's super close and a mind game, it comes down to centimetres and inches. Hopefully it provided some entertainment.
“The continues our domination and closes it out, we've won every gold since 2000, we own it.
"I'm so proud, there is such heritage in the Finn and it's a shame it's leaving the Games. To follow legends like Iain Percy and Ben Ainslie, they were my heroes growing up.”
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here