Cumbrian swimmer Luke Greenbank was part of a four-strong men's Team GB medley relay team who took silver in the men's 4x100 metres medley relay final.
Greenbank, along with Adam Peaty, James Guy and Duncan Scott, finished 0.73 seconds behind the United States, who claimed gold in a world record time of three minutes and 26.78 seconds.
Britain's eighth medal - with four golds, three silvers and a bronze - in the final swimming event in the Japanese capital bettered their previous best tally in the pool of seven gongs, set at the London Games 113 years ago.
It caps a remarkable games for Greenbank, who won bronze in the 200m backstroke final on Friday.
Greenbank's team-mate Adam Peaty believes the "pain" at settling for silver in the men's 4x100 metres medley relay shows how much progress Great Britain has made in the pool in the last decade.
"I don't want to take anything away from the American team," Peaty said.
"They stepped up big time. They knew they had to step up big time. It's an Olympic silver, people would die for that.
"We will enjoy it but there is a little bit of pain there. Maybe you need that. Maybe you need that going to Paris (2024). Ten years ago we were happy making finals. We aren't happy making finals anymore.
"We are happy doing silver and medalling - that's the culture that is different now - and that's part of our success. We are aiming for gold, we are aiming to be the best in the world and dominate the world.
"By the time Paris comes around, we are going to develop. A lot of teams are going to look at us. We are always looking for gold and for world records, I'm incredibly proud to be part of this team - it's history-making."