Adam Peaty has revealed Great Britain's resurgence in the pool is down to tireless commitment behind the scenes after the team equalled their best ever swimming medal haul at an Olympics.

Peaty and James Guy bagged their second golds of Tokyo 2020 and Kathleen Dawson and Anna Hopkin their first, as the Team GB quartet set a world record time in a gripping final of the inaugural mixed 4×100 metres medley relay.

Britain were therefore left celebrating their fourth gold of these Games, to go with two silvers and one bronze, matching the exact haul they achieved 113 years ago in London, and there is the prospect of more to come on Sunday.

Their achievements represent a massive turnaround from when British Swimming's funding was slashed after a failure to win a race at London 2012, and Peaty insisted assiduity and diligence has been at the core of their revival.

"I hope this team and the rest of British Swimming get the recognition and the respect that they deserve because it's been f*****g hard," said Peaty, who retained his men's 100m breaststroke title earlier this week.

"It's the only way to get the emotion across. Honestly people don't understand how hard it is. Hopefully people back home can understand that.

"I've been doing this for seven years since 2014 and I didn't think the team would be where they are today. You've got such amazing talent. It's just incredible to be part of that and hopefully people back home are pretty pumped."

Peaty will be eyeing a fourth Olympic gold and third in Japan this week in the men's 4x100m medley relay final on Sunday, but he feared the worst on Saturday morning after thinking Guy had jumped in too early at their handover.

Britain jumped from sixth to fourth at the halfway stage after Peaty's incredible breaststroke split of 56.78 seconds before Guy catapulted them to top spot with an equally astonishing time of exactly 50secs in the butterfly.

But Guy himself worried he had set off a fraction earlier and did not allow himself to get carried away with the celebrations until he knew he would not get disqualified.

"I was just panicking and panicking. I thought I went early. I was like 'oh no'," said Guy, with Peaty adding: "I saw his feet leave and I was like 'you f*****g idiot."

Guy added: "As soon as I dived in I'm thinking 'I've gone too early, I've screwed it up, I'm going to get a DQ, but you know, it's too late now, just go for it'. Afterwards I was just waiting and just saying 'please, please, please, please...'"

This event has been added to the Olympics schedule for the first time – where two males and two females must be selected but the nation can use any combination in the backstroke, breaststroke, butterfly and freestyle splits.

Dawson did not get off to an auspicious starts after slipping in her push off the wall in a leg where she was up against four males, including the 100m and 200m backstroke winner Evgeny Rylov of the Russian Olympic Committee.

"I had a little bit of an issue," said the Scot. "I couldn't quite feel my hands. Somehow I slipped going in.

"I wasn't quite sure what I did...when I did it. I think I managed to keep calm and after that it was about focusing to try and get the best performance I could out of myself."

Britain were six seconds off the pace when Peaty dove in but the 26-year-old from Uttoxeter and Guy helped their nation into a lead of six tenths of a second as Hopkin anchored their race in the freestyle.

Hopkin came into the race knowing she would go head-to-head against the men's 100m freestyle champion Caeleb Dressel but the American was well back as Britain touched out in three minutes and 37.58 seconds.

"It's pretty cool to say I've beaten Caeleb Dressel," joked Hopkin. "To know that he was coming for me, it's a little bit intimidating. But I knew that the guys ahead of me would get me a good lead.

"And then it was just about me focusing on my own race and keeping my head down, not worrying about where he was. Because that would just distract me, and stay focused on my lane and bring it home for the guys."

China took silver, finishing 1.28 seconds behind the winners, while Australia collected bronze as the United States settled for fifth.

Elsewhere, Ben Proud qualified for the men's 50m freestyle final on Sunday, the final day of swimming at the Games.