Just a few hours into his eight-day swim down the entire length of the Thames, David Walliams suffered his first setback.
The comic was forced to put on a wetsuit after his skin turned blue – a sign of hypothermia.
David admitted he was "daunted" by the way the charity challenge had started out.
"The first section of the swim has really shocked me.
"The water is two degrees colder than when I swam the Channel, just 15 degrees.
"It's made a massive difference to how I’ve been able to cope.
"Even though I don’t like swimming in wetsuits because they’re restrictive, I just had to wear one.
"Even if it only makes me think about the cold every ten seconds rather than every five seconds."
Earlier he'd been seen off in Lechlade, Gloucestershire by the two special 'ladyees' in his life – cover girl wife Lara Stone and his mum Kathleen – and hundreds of supporters.
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