Heard the one about the comedian with no experience of open-water swimming taking on the English Channel known throughout the world as the blue riband event for the sport?   Well, yes, you probably have; Little Britain star David Walliams' exploits for Comic Relief last year captured the public's imagination and hearts, as he raised over £1m for the charity.  So, consider that a warm-up introduction and we'll start again: heard the one about the sports scientist who made it all possible? 

Step forward Professor Greg Whyte, who had the very serious job of making sure Walliams was up to the challenge.  How did it al come about?

"David was returning from a visit to Ethiopia and on the plane ride back he made the schoolboy error of telling a charity worker that he'd like to do something, and suggested the Channel.  Steve Cram - a friend of mine - knows Kevin Cayhill, who is the chief executive of Comic Relief", Whyte explains. 

"Within three days he was in my lab undertaking cardiovascular assessment." 

Whyte's electric career history made him perfect for the job of turning a comedian into an athlete.  He studied sports science and a PGCE in physical education at Brunel University before studying a Masters degree in America. Two years later he was back in the slightly less glamorous surroundings of Wolverhampton, where he did a joint PhD between the university and St George's medical school in London. 

His stay in Wolverhampton last seven years in a role that ultimately became that of a principal lecturer, before moving the Olympic Medical Institute for four years as the director of research.  Following a further two-and-a-half years in a similar role at the English Institute of Sport, he now works at Liverpool John Moores University. 

"I'm professor of applied sport and exercise science at LJM which takes up an awful lot of time," says Whyte, who is a BASES high performance sport accredited physiologist. 

"My specialist area is cardiovascular physiology.  Then I tend to be fairly electic: "I'm director of science for the Irish Institute of Sport, the director of the Cry (Cardiac Risk in the Young) Centre for Sports Cardiology at the Olympic Medical Institute and I also do research work in high-performance sport and within cardiology" 

There hasn't always been such a range of opportunities, however. 

"In the mid-to-late-Nineties there weren't really any jobs in sports science," he says. 

"I was working with Benetton Formula One Racing and I was the only physiologist across the whole of motor sports, so that gives you an idea as to how new the field is.  Sports science is very different to what it was in the Seventies and Eighties.  The depth and breadth of skills that are required, including the ability to communicate and work alongside others, is very different." 

If there was such a paucity of employment options, what made Whyte want to get involved?" 

"I was an athlete as a child, then I was a swimmer and then I moved on to the modern pentathlon.  For multi-disciplinary sports you have to be extremely disciplined but you also have to have a real understanding of how to structure your training to optimise it across multiple events, and sports science leads naturally on from that." 

Indeed, Whyte's involvement in the modern pentathlon went well beyond childhood.  He represented Great Britain for 1986-2000, including the Olympics of 1992 and 1996, 10 World Championships and six European Championships.  Highlights of his medals haul include a silver and bronze medal, won at the World Championships respectively. 

"|n those days there was no world-class funding," he says. 

"However, what it did is made me extremely hungry - I had to give up an awful lot to be able to train and compete.  I think the money that has come in (to athletics) has freed up a greater opportunity for training and recover.  At the same time, I do worry that it has reduced that hunger in certain individuals.  I did it as I did it and had a wonderful successful time, but I don't think I'd do it again.  Too hard!" 

You'd think that last sentiment is the one David Walliams would have been most inclined to voice when training began. How did it get beyond him just dipping his toes in?" 

"(David's) obviously physically talented but he could just about swim a mile, and that was our starting point.  Technically, he was poor, physical capacity OK - for a comedian," says Whyte.

"I met him one every two or three weeks.  We were in constant telephone and e-mail dialogue and in the early stages it was very much hands-on because there were a lot of technical issues.  My job was to make sure he stayed safe.  I became a mentor.  It moved from instructor, to trainer, to coach, to mentor, and it was really about making sure he was optimally prepared to be able to make a serious attempt."

After 11 months of training, including practices in the warm waters of Croatia, it finally came down to the day of the swim and Whyte was there every stroke of the way. 

"I did all the greasing and the feeding - we have drinking bottles on a rope that are thrown to him and food stuffs in a cup on the end of a pole.  It's a very difficult task to do well because there are all sorts of problems in open water, particularly the Channel. 

"Not the sort of problems you come across at your local swimming baths either - think dodging sewage, shoals of jellyfish and the occasional passing ferry. 

"I was in the water every other hour, so I was actually swimming for five hours too," says Whyte. 

"The thinking behind that is that David has a little bit of company - it's a lonely place out there - and to make sure that the pace is achievable and maintained." 

Which, of course, it was - Walliams completed the swim in 10 hours and 34 minutes, making him one of the 50 fastest people to so out of 1,171 attempts to date.  Whyte wasn't surprised. 

"If you'd asked me in the August of the year prior I would have said 'no chance'.  If you'd have asked me at Christmas I'd have said 'slim chance', and if you'd asked me at Easter I'd have said 'every possibility.'

He is a wonderful person who has enormous athletic talent and is a very good example of the ability to apply your mind to something and actually achieve.  He's an outstanding role model for any young kid out there." 

the praise was returned in kind by Walliams during his acceptance speech for a BBC Sports Personality award last year. 

"I was very lucky in having the most amazing trainer in Greg Whyte, who got me all the way across, so I must share this award with him," he said.

Walliams' exertions even inspired Whyte to have a go at the Channel a month later, but with less favourable results. 

"The important point to make is that only 40 per cent of people are actually successful swimming across the Channel and more often that not it's the weather that is the critical factor," he says. 

"I got dragged out two miles from the French coast because of a change in weather.  I was on for an eight-hour swim but spent two hours going nowhere until the crew dragged me out." 

However, in the spirit of battling against the odds and on the back of such a successful career, White will surely try again?

"Um, probably.  It's not a decision I take lightly."