Funny man David Walliams is planning to swim the Strait of Gibraltar alongside Olympic rower James Cracknell.

The Little Britain star is expected to join the 35-year-old - who is currently midway though an attempt to reach north Africa in seven days of rowing, cycling and swimming - later this week.

Cracknell set off on the challenge last Wednesday to raise money for Sport Relief.

Banstead's Walliams will act as Cracknell's friend and coach as they undertake the feat.

The challenge is nine miles less than crossing the English Channel - which Walliams, 36, completed in July 2006 in just over 10 hours.

He said: "It's really James's challenge. I'm just jumping in at the end to get some of the glory."

For more information on Sport Relief click here.