British funnyman David Walliams has cancelled his work commitments for the rest of the year (13) as he prepares to undergo back surgery. The TV star has been battling pain since damaging a spinal disc during a gruelling eight-day charity swim in London's River Thames in 2011. Doctors have now told Walliams he will have to undergo an operation this week (beg25Nov13), prompting him to postpone several work commitments, including his World of Walliams book event, which was scheduled for 7 December (13) in London. The event has been moved to March next year (14). Walliams apologised to fans in a statement on Tuesday (26Nov13), writing, "I am so sorry the mega-book event has had to be postponed. Everyone has put so much work into it and I was really looking forward to it. "Unfortunately the operation on my back is long overdue and can't wait a moment longer... The doctors have ordered me to rest for the remainder of the year so I can recover. Fortunately we are able to reschedule the event for March, and hopefully I will see most of you there. I wish you all a very merry Christmas."