David Walliams and Gary Barlow are joining Chris Moyles, Kimberley Walsh and Fearne Cotton to take over the voice of the BT speaking clock for Sport Relief, between today and April 9.

BT hopes to raise £1m over five weeks and is running daily competitions for callers to guess the mystery celebrity voice. David Walliams said, 'I was relieved to hear that BT only wanted my voice this time around, and not for me to take on another gruelling challenge'.