LITTLE Britain star David Walliams has embarked on one of his most strenuous challenges yet.

And Oxfordshire fans can catch a glimpse of the comedian as he attempts an eight-day bid to swim the length of the River Thames.

Yesterday morning Walliams slipped into the Thames at Lechlade to raise money ffor Sport Relief. The aim is to make it all the way to Big Ben in London. For the next two days, he will be swimming through the murky waters of the through Oxfordshire.

And he is calling on locals to come to the riverbank and wave him on as he passes.

Walliams, who described himself as a “masochist” for taking on another swimming challenge, said: “I wanted to do something else. I’d just turned 40 and I thought I haven’t got much time left because my body is falling apart.

“I thought I better get on and do something because one day it’s going to be too late.”

Walliams swam the English Channel in 2006 and raised more than £1m for Sport Relief.

His new challenge, at 140 miles, is seven times the distance.

Walliams said: “The nice thing about this, as opposed to the Channel, is that people can come out and see you.”

He arrived in Oxfordshire yesterday afternoon and stopped for lunch at Tadpole Bridge near Faringdon, before finishing his first day in the water at Bablockhythe.

He sets off from the Ferryman Inn at Bablockhythe at 8.20am today, swimming through Swinford to Oxford.

After a lunch break, he will get back into the water at Folly Bridge at 3pm, and hopes to finish his second day of the challenge at Abingdon Bridge by 7pm.

Starting at Abingdon Bridge tomorrow at 8.30am, he will carry on through the county until he reaches Shillingford Bridge for a quick break.

He will restart his swim at 3.15pm and aims to finish his Oxfordshire section of the challenge at Goring Lock at about 7pm.

Walliams will burn the equivalent of 4,400 calories every day while he contends with unpredictable currents and powerful undertows.

He said: “I think about happy things. I think about what I’m going to eat when I get out.”

He talked about a 12-year-old homeless boy called Philip he met on the street in Kenya.

Walliams said: “Sport Relief funds a centre that gives him education, food, shelter and healthcare. I think about him because he is such a sweet boy, with so much hope. I think about him and not wanting to let him down.”

As well as busy river traffic, Walliams will be trying to avoid accidentally gulping any of the 39 million cubic metres of sewage that ends up in the Thames each year. And in his first day, he had already had an encounter with a swan.

Walliams can be sponsored at sportrelief.

com/walliams, where there is a GPS tracker of his progress.