Published Friday, 30 March 2012
The Little Britain star was invited to meet Cameron at his home in London's Downing Street to discuss his 140-mile marathon swim in the Thames to raise money for the Sport Relief charity.
But Walliams didn't sugar coat his experience when questioned by the PM, who told him: "You swam through my constituency at Letchlade... I thought when you were doing that bit, I thought that looked all right. Then when you started getting closer to London..."
Walliams replied: "Once you get to the Thames in London, it's disgusting. The water stinks, and it's brown. No one on a bridge in London has looked at the water and thought about going in."
Comedian John Bishop, retired rugby star Josh Lewsey and TV presenter Helen Skelton also joined Walliams at the meeting with Cameron after raising millions for the biennial charity event.