Lewis-Francis finished a poor fifth in his quarter-final in Helsinki

Eton-based Lester already trains British athletes Marlon Devonish and Tim Benjamin and Lewis-Francis hopes the switch can kick-start his career.

The 22-year-old won the world junior 100m crown in 2000 but has yet to win a major senior individual outdoor title.

"I've been in Birmingham training on my own and it hasn't worked. Working with a group will push me harder," he said.

But the Birmingham-born runner said the decision to leave Platt - his coach of 10 years - had been the "hardest decision of my life."

Steve Platt will always have a place in my athletics career Mark Lewis-Francis

He added: "Steve Platt will always have a place in my athletics career. I've had a great relationship with Steve - he has been there from day one and has been a father figure to me."

Lewis-Francis revealed he first considered switching coaches a year ago but put the decision on hold after winning Olympic gold with the Great Britain sprint relay squad in Athens.

But 2005 has been full of frustrations - he tested positive for cannabis at the European Indoor Championships in March, has been constantly dogged by a hamstring injury and failed to go beyond the quarter-finals of the 100m at the recent World Championships in Helsinki.

Lewis-Francis also faced criticism for failing to develop the huge potential he showed as a teenager in the build up to the worlds.

Top coaches attack Lewis-Francis

Former 100m world record holder Maurice Greene's mentor Jon Smith and Trevor Graham, coach to world and Olympic 100m champion Justin Gatlin, both accused the then Birchfield Harrier of not pushing himself.

Gatlin and former Olympic champion Donovan Bailey were subsequently reported to have made offers to help the Briton realize his talent.

Despite going on to help Britain to sprint relay bronze in Helsinki, Lewis-Francis has finally accepted the need for change, but opted to remain in the UK.

He will now relocate his family - girlfriend Nicola and three-year-old son Romeo - to London to be close to his new training base at the Thames Valley Athletic Centre.

"It's going to bring my potential and talent out," said Lewis-Francis, who also hopes a fresh start with Lester - who has been appointed senior performance coach for sprints by UK Athletics (UKA) - will help him put the cannabis incident behind him and help him rediscover his passion for his sport.

"Wrong place, wrong time," he said of the drugs matter.

"I was in a club and it was another angle in my life that I really regret.

Still not sure if staying in the British environment will really do it for him From D Have your say on Five Live

"Obviously this is going to haunt me for the rest of my life but hopefully it's something that will not trouble me again.

"I will be down in London training as hard as I can and hopefully it will be forgotten. This is a new place in my life and hopefully I can move on.

"I began athletics not to be a big celebrity or a big idol. I did it because I loved the sport.

"I've lost that somewhere in the last couple of years and I want to start enjoying it again. I want to get back to being the old me, enjoying what I do best and that's running fast.

"I was on the brink of leaving (Platt) last year but had to give it one more year after the Olympics.

"It's just about moving to the next level and that's something me and Steve didn't achieve. We've looked at every coach in the world and have seen what Tony Lester can achieve with athletes.

"He's a talented man so I'm putting my life in his hands. People are forgetting I'm only 22. Linford (Christie) didn't start running fast until he was 25 or 26."

Lewis-Francis' decision was backed by UKA performance director Dave Collins.

"This is a move in which we have been completely involved and we are very happy to see it," Collins said.

Lewis-Francis also revealed he was undergoing an MRI scan on his problem hamstring in the capital on Monday.