When Little Britain star David Walliams stepped up to tackle a staggering cross Channel swim challenge this week, he was relying on 'made in Luton' know-how to see him through.

It took the award-winning comedian just 10 hours 25 minutes to reach the French shore from his Dover departure point - a speed fast enough to earn him a place in the elite top 50 who have taken the plunge. 

And to get in shape for his epic Sport Relief charity challenge, the 34-year-old was put through his paces by former Luton schoolboy and sports supremo Professor Greg Whyte, whose parents live in Crawley Green. 

Greg's dad George accompanied the duo on several training sessions and says he was amazed that David had never competed professionally. 

"I thought he was a very strong swimmer when I saw him in the water at Lake Dorney, near Reading.  He and Greg got in at the boat house end and swam the length of it. 

"I could hardly believe it when he said he'd learned at school and was nothing special."

George says his son rang with regular updates during David's successful bid to swim the Channel:

"Greg spent an hour in the water, then an hour in the boat. 

"He called on his mobile when they were half way across and again when they turned round to come back, but I couldn't hear much because of the wind." 

George says he warmed to Walliams immediately:  "He's just an ordinary guy.  As Greg says, the sort of bloke you'd like to have a beer with. 

"One time when we were together someone came over and said there were some kids upstairs who wanted to meet him.  So he just upped and went with this fella to see them."   

Greg has described swimming the Channel as "one of the toughest physical challenges on the planet."  Fewer than 10 per cent of those who attempt it succeed. 

The famous stretch of water is one of the world's busiest shipping lanes, with 600 tankers and 200 ferries crossing it every day. 

Walliams, who expected to take 14 hours for his marathon swim, said he was "relieved and pleased" with the result: 

"And I feel we needed a happy ending to this story.  It's taken the sting out of the the World Cup." 

Greg, a former Olympic athlete, hinted at the Channel challenge during an interview with our sister paper, the Luton News, in January. 

He admitted he and David were involved in a "secret project" after the pair were spotted emerging in wetsuits from rivers, swimming pools and beaches across the country: 

"We've been training all over the place - Portsmouth, Newcastle, wherever he's working or appearing.  We've even swum up the Thames. 

"David's extremely fit and he's not a bad little mover." 

There will be a fitting finale tonight at the Houses of Parliament when Greg hosts a gala evening for the charity CRY (Cardiac Risk in the Young).  He is honorary chairman and David will be his guest of honour. 

A documentary about the swim called Sports Relief Presents Little Britain's Big Swim will be shown on BBC1 next Thursday at 8pm.