It is more than four years since Mark Foster publicly fell out with the then boss of Britain's swimming team but the animosity is still there.

Foster can hardly bring himself to mention the name Bill Sweetenham - now departed for his native Australia - who he blames for denying him a place at the Athens Olympics.

Foster has staged a remarkable comeback, emerging from retirement to book a place at the Beijing Games where he is assured of records before he even takes the plunge.

Aged 38, he will be the oldest ever British Olympic swimmer and the oldest swimmer at this summer's Games. Beijing will be his fifth Olympics and he will be at least 10 years older than any other British squad member.

Foster says he is revelling in the less disciplinarian approach under Michael Scott, the former director of the Australian Institute of Sport who replaced Sweetenham almost a year ago.

"It's a lot more relaxed and upbeat," he said. "With him [Sweetenham], he was a bit of a dictator. In the team you had got swimmers aged 16 up to my age, but he treated us all like kids.

"Things have changed. Michael Scott is a lovely guy. He says, 'I don't coach but if you need anything come and ask me.' Sweetenham was more like: 'You don't know anything.'"

A specialist over 50metres, Foster has won 19 titles in World, European and Commonwealth competitions, yet having competed in Olympics since the Seoul Games in 1988 he has yet to collect a medal.

He faces an onerous task to break that duck in Beijing as the world's best in the 50m freestyle event get quicker. Foster qualified at Sheffield's Olympic trials in 23.29 seconds - just months earlier Australian Eamon Sullivan beat the world record in 21.56 secs.

Despite the widening gap, Foster recently rejected the new Speedo LZR Racer bodysuit - which has been worn by 17 record breakers this year - and calls for a return to the era of trunks and bikinis.

"I wouldn't stand on block without thinking I can win it. But I'm not stupid. I appreciate people have got very quick though a lot of those times are done with the new suits. I've only worn the old suit. The new suit is giving people a two per cent advantage which is half a body length. I don't want swimming to become like Formula One where the driver with the best car wins the race."

Foster's tips for British success in the pool are Liam Tancock, in the 200m individual medley and Rebecca Addlington in the 800m. Britain's best chance of a swimming medal is not in the pool but the 10k "open water" swim which he believes Welshman David Davies could win.

Since qualifying for the Olympics, Foster has been training in Italy and recently completed filming an episode of Superstars. However, he is forbidden by Channel 5 to reveal how he fared until the recently revived mini-Olympics is screened in July.

After training in the United States, he will join the British team at their camp in Osaka, Japan, where he will rise at 5am to prepare for the Olympic finals, which will be staged in the morning to suit American television audiences eager to follow Michael Phelps's pursuit of multiple golds.

At his fifth Games, Foster will naturally be cast as a mentor to debutantes. His advice? "Sweetenham - I don't like using his name - said it would be unforgiving and unrelenting so people walked out there and they were scared," he said. "My advice would be to treat it like any other competition."

•Mark Foster is supporting Lloyds TSB's "Local Heroes" scheme in partnership with Sport Aid to provide £1million funding to young talent in Olympic sports.