Smeared in goose fat, David Walliams swims the Channel

Clad in the briefest of swimming trunks and smeared in goose fat, David Walliams might have simply been trying out a new Little Britain character yesterday.

But instead, the comedian who bade his parents a fond farewell on a Dover beach at sunrise before plunging into the icy waters of the Channel was about to perform a sporting feat. Ten hours and 34 minutes later, the 34-year-old arrived in Cap Griz Nez, France, having swum more than 21 miles and raised more than £400,000 for Sport Relief. Walliams negotiated one of the world's busiest shipping lanes to do so, not to mention jellyfish, sewage and debris in temperatures of around 15C.

"I was thinking about lots of Pet Shop Boys songs, Morrissey songs and Abba songs, it helped to calm me down," the comedian said as he headed back to Dover by boat last night.

"I've been told that my time puts me in with the top 50 Channel swimmers of all time, how did that happen? I've never done anything sporty before, I don't know what happened. I think it must be all the good vibes. I did it much faster than I thought; I thought I would do it in about 14 hours. I feel relieved, I felt there needed to be a happy ending to this story and there is."

Chomping on bananas and chocolate bars that were handed to him by pole from an accompanying boat, he completed the swim in good time as a helicopter and coastguard spotter plane flew overhead.

The Channel Swimming Association chairman Michael Read, who is the "king" of the sport, having completed the crossing a record 33 times, kept a watchful eye from the boat. Mr Walliams, he said, had remained "remarkably calm".

"The last mile, and then the last few yards, are the most difficult. Everything seems to go against you, you're exhausted, your body feels like lead and seeing the end in sight doesn't necessarily help," said Mr Read.

Despite the fact that 600 tankers and 200 ferries cross the Channel each day, Mr Read explained that the most imminent danger was from jellyfish.

"We've seen some of the larger ones, but there could be lots of little jellyfish in there too which could catch him," he said halfway through the swim.

Meanwhile Walliam's trainer, the former Olympic pentathlete Greg Whyte, watched for any signs of hypothermia.

The 34-year-old agreed to the challenge after witnessing the problems faced by the people of Ethiopia during a trip with his fellow Little Britain star Matt Lucas. In the past 11 months, he has undertaken a rigorous training programme under Whyte. It included swimming for up to eight hours in one go, and spending time in a special "cold tank" to acclimatise his body to the chilling temperatures.

"The first time I swam in a lake at that temperature as part of my training, I started hyperventilating with shock. It's difficult to get your head round just how cold it is," he explained.

Walliams being a comedian, the only cloud on the horizon was the vague suspicion that the whole venture was some sort of spoof.