The disgraced 30-year-old sprinter spoke to A-level sports science students and elite athletes at the school on Monday evening.

He is touring the country in a bid to rebuild his image after testing positive for the banned steroid THG five years ago.

Chambers hit the headlines in July when he lost an appeal to overturn a ban on him competing at the Olympic Games.

But he is allowed to run for Great Britain at other events and says he wants to make a fresh start in the sport and prove he can run clean.

Before speaking to Oakham students this week he told the Rutland Times: "I am putting across a message that I wish I did not go down the road I went down.

"I've destroyed my reputation and my career and I wouldn't want anyone else to do the same thing."

Chambers believes he can pass on a valuable lesson to young people. He has already visited inner city schools in London and is due to speak to the Oxford Union later this month.

He said: "The advice I will be giving to these young sportspeople is to be smart about any decisions they make about their careers. I will advise them to look out for certain individuals – the snakes in the grass – who will try to make them go down the wrong path."

Chambers has admitted taking THG for 18 months before he tested positive in 2003 and he said he took other banned performance-enhancing substances.

He was stripped of his 100m gold medal from the 2002 European Championships and the gold he won in the 4x100m relay. The athlete was also made to pay back all the prize money he won going back to 2001.

Chambers appears genuinely contrite. "I was in the wrong place at the wrong time and I was being wrongly advised. If anyone is considering doing what I did they only have to look at what happened to me," he said.
It was a sobering experience for Chambers as he watched the Beijing Olympics at home on television this summer.

He saw Jamaican sprinter Usain Bolt scorch to world record times in winning both the 100m and 200m titles.

The challenge for him now, he says, is to prove he can compete with the top athletes at next year's world championships in Berlin without taking drugs.

"It was Usain Bolt's time in Beijing and he shone," added Chambers. "It was exciting to watch him do what he did. He made it a great spectacle with his performance in the sprints. I'm confident I can beat him when I get the chance next season.

"I'm looking forward to competing at the world championships and taking on Usain and the others. I have proved I can take on the Jamaicans and the Americans and I will be going out to put medals on the table for Britain. I'm born to run. I've got three good years left in me and I'm going to prove I can run clean."

In his talk at Oakham School, Chambers responded honestly to questions and told students what drugs he had taken and where he had got them from.

School director of sport Iain Simpson said: "It was very useful from the students' perspective. Dwain was very open and the kids asked some very intelligent questions."