Walliams 'quite tired' after his epic swim

He swam for 140 miles, burning 70,000 calories and lifting his arms for 110,000 strokes after plopping into his Thames at its source in Gloucestershire just over a week ago. His assessment yesterday, after completing his epic challenge: "I feel quite tired, I'll be honest with you."

David Walliams dragged his weary limbs from the water opposite Westminster shortly before 6.30pm to cheers and tears from crowds lining the river banks, some of whom had helped him raise more than £1m for Sport Relief.

When asked on live evening television news what the most difficult part of his was, he replied: "Feeling like my arse was going to explode for two days."

"Thames tummy" has been an almost constant companion as Walliams swam through increasingly polluted waters.

After a quiet start at Lechlade in Gloucestershire last Monday, Walliams' feat gained a dedicated following as bystanders cheered a growing flotilla of boats and kayaks that have surrounded the tiny silver dome of his swimming-capped head.

They watched the metronomic sploop, sploop, splooping of his arms, a peculiar spectacle that has captivated a nation.

The final stretch, down the tidal portion of the Thames through central London, was supposed to be the hardest part of all. In fact the outgoing tide propelled him along at a speedy 5mph.

"I never expected this to catch the public's imagination like it has," Walliams said, during a five-hour lunch stop at Kew as he waited for the tide to change before beginning the most gruelling final stretch of the swim through the choppy, sewage-filled waters of the Thames in central London.

"He's the, sort of, nation's sweetheart," said his mother, Kathleen. "People think they're part of this because they can actually see him doing it. He rescuing dogs and waving to people when he all wants is to lay down almost. I'm very, very proud of him."

At Cookham Lock in Berkshire on Saturday, Walliams helped Vinny, an over enthusiastic labrador, from the river. Vinny suffers from a bad hip, and couldn't make it out unaided.

Almost two hundred seven to 11-year-olds – the entire upper school of Kew Green Prep School – lined the banks as he swam past yesterday morning, screaming, "David! David! David! David!" A cursory wave from the man himself, and they all went a little bit nuts.

"I just think it's so inspiring, what he's doing," said Caroline Sutton, who watched from the bank with her four-year-old-son, Max. "When you see him coming you almost well up. I don't know how he's doing it."

Comedians Jimmy Carr, Miranda Hart and Rob Brydon have all been out to support him as he made his epic journey, as has former talk show host Sir Michael Parkinson. Yesterday the support boat containing Walliams' wife, Lara Stone, ran aground in a muddy section of the river as the tide began to change direction. The supermodel had to be rescued by a second boat operated by a sponsor.

One hundred amd forty miles is about seven times the distance across the English Channel, which he swam five years ago, again raising more than£1m.

Walliams is a strong, but by no means professional standard, swimmer. However, as his efforts have amazed and inspired the general public in equal measure, even former Olympians have been impressed.

"What makes it so hard is doing it in dirty water with low visibility and tides while swans are attacking you – it's a very impressive achievement," said Sharron Davies, the former Commonwealth swimming gold medallist.

As Walliams plopped into the water at Teddington Lock, at 6.45am yesterday, he looked exhausted.

"Every part of my body aches," he said in an interview with Radio 1 DJ Chris Moyles.

"I'm going a little bit loopy because I've just been looking down at the dark water for about 12 hours a day... I am excited because I've had enough of swimming," he said.

"To be honest with you, I'm kind of over swimming now and I need to just have a nice lie-down."