FORMER Formula One world champion Jenson Button swapped his McLaren racing gear for a wetsuit at the weekend as he swam, biked and ran for charity on Sunday.

The racing ace was joined by Olympic silver medallist Lizzie Armistead and Sky Sports F1 reporter Natalie Pinkham at Luton Hoo to raise funds for Help for Heroes.

The trio were part of a 500-strong field competing in the annual Jenson Button Trust Triathlon. Also at the triathlon was Force India driver Paul di Resta. About 2,000 people, including supporters, attended the event.

The initial heats comprised a 300m swim, 9km bike ride and 2.5km run, followed by a longer final course of a 750m swim, 20km bike ride and 5km run, all at Luton Hoo.

Jenson trains for such events with his triathlon team which includes Tommy Vonach of Austria and Fraser Thomson, who went to school with him.

A curious crowd quickly gathered around Jenson as the F1 star was interviewed for television before his heat.

Asked how he felt, Jenson admitted that it was nerve-wracking but he expected the adrenalin to kick in before competing.

He added: “It’s a great release from motorsport. This is a great family event, and there is a festival vibe.”

Jenson said racing in triathlons worked “pretty well” alongside his F1 career – he was the F1 World Champion in 2009 and second in 2011.

While he is good at all three disciplines, he admitted that cycling “is probably my best”.

Natalie Pinkham admitted she had partly “copped-out” in the race as the television presenter competed in the running section, while Lizzie cycled and Julia Wurz, the wife of former F1 driver Alexander Wurz, swam.

Natalie joked: “I was the weakest link.”

Motorists from St Albans attending the event smiled when a spokesman from event organiser, Human Race, warned triathletes to “watch out for potholes” while cycling.

There was a huge cheer for Jenson as he competed in one of the men’s heats, securing seventh place and going through to the final.

The women’s final was won by India Lee in 55 minutes and 24 seconds, while the men’s champion was Gavin Noble (47.34).

Among those competing was a team from Aldershot, all members of the Grenadier Guards. Captain Andy Butcher said: “We went well, I really enjoyed it. The swim was fun but the cycling course was a bit cheeky as we had to start it on a hill. But it’s a great course, and a brilliant event.”

Triathlete Tommy Vonach said: “It is such a fun course, and it’s like a big triathlon party – it’s our sport at its best.”

After the race Jenson said it was great to hear that close to £30,000 had been raised for Help for Heroes, a charity which supports veterans and serving personnel who have been injured, wounded or become sick as a result of serving their country.

• CleanFeed Media has produced a video of the event, available on YouTube which features interviews with Jenson along with Professor Greg Whyte, who coached television star David Walliams to swim the Channel and the Thames.