Little Britain star David Walliams said he never expected his Thames swim to capture the public imagination in the way it did.

The comic entered the seventh day of his epic attempt to cover 140 miles in the water, supported by fans and celebrity friends along the way.

He aimed to finish the day in Teddington, saving the tougher tidal section of the Thames for the final day of his gargantuan challenge on Monday.

Walliams said: "The two things that have really kept me going so far are the updates of the fundraising totals I'm given and the stunning support I've been given by the public. There must have been tens of thousands of people along the route and I can hear their cheers as I'm swimming.

"I never expected this to catch the public's imagination like it has - there seems to have been a real carnival atmosphere around it which is lovely. Tomorrow will see me entering the tidal stretch of the Thames with all the dangers that brings, so I'll need to be strong."

The tidal Thames stretch of the course has strong currents and undertows and is busy with river traffic.

Walliams has raised more than £800,000 so far in his BT Sport Relief Challenge. He and his support team decided to carry on with the swim despite news that 500,000 cubic metres of sewage has entered the river in the past week.

The comedian received inoculations before the swim and has been taking antibiotics as a precaution because of the filthy water. He has been spurred on by the support of his wife Lara Stone, who has been travelling in a boat alongside him.

A series of famous friends have also turned out to cheer him on, including yesterday comedian Rob Brydon and TV veteran Sir Michael Parkinson.

Supporters can sponsor the performer at www.sportrelief.com/walliams. There is also a GPS tracker on the Sport Relief website showing where he is, and a regularly updated Twitter feed.