The International Swimming League: a cross between a raucous nightclub and an Olympic swimming venue

It was the sight of a DJ, mixing away on his decks at vast speed and volume while situated directly behind a grey-haired and bespectacled start-line judge, which really confirmed that the International Swimming League is something very different.

For one weekend only, the London Aquatics Centre resembled a cross between a raucous nightclub and an Olympic swimming venue as London Roar - Adam Peaty’s team - were overhauled in the 37th and last race of the meeting but still qualified for the ISL’s inaugural Grand Final.

The location for that showdown will be Mandalay Bay in Las Vegas, just four days before Christmas, when two teams from Europe and two from the United States will compete to be crowned inaugural champions in swimming’s revolutionary new competition.

Despite the narrow team defeat, Peaty certainly still sent a sell-out London crowd home happy by winning his favoured 100m breaststroke event after overhauling Ilya Shymanovich with an extraordinarily rapid final length. The added technical importance of the starts and turns means that the short-course 25m length format of the ISL is not ideally suited to Peaty’s pure swimming power but, despite the rare experience this weekend of also losing the 50m breaststroke, he is revelling in the team format. When Peaty was not racing, he was invariably topless poolside and either conducting the crowd or shouting on and high fiving his team-mates. He was also drafted in as an emergency option in the 100m mixed freestyle relay, even if he was clearly still smarting from his rare defeat over 50m on Saturday. “Don’t get me started on that 50m,” he said. “You make a mistake in the 50m, especially short-course, and you are out of the game. I made two or three mistakes. It’s the first time in a long time that I have come fourth but it’s good for the sport and me. When I lose, I come back faster - I will use that as fuel for Vegas.”

Peaty has been among the most vocal proponents of the ISL, which has given swimmers added visibility and races in front of noisy crowds, during what is usually a long lull in their competitive schedule. Although he is currently in the middle of a heavy training block ahead of the Olympics next year, Peaty has been open previously about the difficulty of maintaining focus during long breaks from major competition. “I think London smashed it,” he said. “This is one of the main markets because we are so passionate about sport. It is appealing for that younger audience: straight action, no heats, everything at risk and hopefully this is the start to build proper profiles for these athletes. Without the fans you have got nothing and swimming is a sport for everyone.”

London Roar had earlier been leading for much of Sunday night before the final ‘Skins’ 50m freestyle races - a series of three eliminations that narrow the field down from eight to four to two - before ultimately being beaten by the fellow European-based Energy Standard team.

Their individual star was Chad le Clos, the South African who so memorably beat Michael Phelps in the 200m butterfly final at the London 2012s.

In the very same pool and in front of his family, Le Clos overhauled another world-class field, including Britain’s James Guy, in the final 50m to win the same event and finish the weekend as the meeting’s ‘MVP’ after winning more points than any other swimmer.

“It was a really emotional night,” said Le Clos. “I think any other pool and I would probably have lost that race. I was holding back the tears coming out. Remembered the same sensations, with Phelps behind me. It was special - a bit of destiny.”

Other highlights included Britain’s Holly Hibbott winning the women’s 400m freestyle, Olympic champions Katinka Hosszu and Sarah Sjostrom dominating much of the women’s programme and Minna Atherton going to within 0.02secs of the 200m world backstroke record. Duncan Scott’s versatility, which included a win in the men’s 200m individual medley, was again hugely important for London Roar while the Australian Campbell sisters - Cate and Bronte - agreed that the atmosphere surpassed even the London Olympics. Next stop, then, will be the seventh and final round in the Nevada desert, where Peaty intends to make the most of a pre-Christmas trip both in and out of the pool. “Swimming is the main bit - but get the job done and we can have a bit of fun after,” he said. “It’s Vegas.”