The real wizard of Oz

Today we can reveal that Toto is played by Bobby, a West Highland terrier who has something of a showbusiness pedigree - he is the protégé of former Boomtown Rats guitarist Gerry Cott.

Mr Cott, who founded the group with Bob Geldof but quit before their fifth album was released, has coached Bobby to perform tricks that leave audiences open-mouthed.

Mr Cott, 55, who lives with his wife Cathy and sons Harry, 19, and Sonny, 11, near Leatherhead, said: "He has integrated so well with the cast because he is so calm and relaxed. Our method of training works on the dog's character and confidence, which means they can be comfortable even on stage in front of hundreds of people."

Bobby, who has already made a name for himself in film and TV, is snowy white - the opposite of the black dog Frank Baum's book describes - and has learned to climb ladders, play dead, jump, whimper and howl on command.

He has even developed his own prima donna streak - interrupting Dorothy's rendition of Somewhere Over The Rainbow on opening night with a couple of playful yelps. "It is a bit like, 'Look at me, look at me,' " said Mr Cott. "It was a little unfair of him to muscle in on such a lovely moment in the play."

He and Harry, who is working as Bobby's chaperone during the show's run, spent a week integrating the dog with the cast and teaching Sian Brooke, who plays Dorothy, a series of silent cues to prompt his performance.

Bobby has a rigorous schedule, with eight shows spread out over a six-day week - roughly four hours of acting a day.

Mr Cott, who was born into an Irish farming family, said he enjoyed working with animals and that his time with the Boomtown Rats had helped him gear his training towards the film, music and television industries.

He said contrary to some rumours, Bobby was not named after Geldof. The dog was originally called Billy but after his film debut, starring in The Adventures Of Greyfriars Bobby, the new name stuck. The Cotts, who own dress designing company Phoenix Cobham as well as running Dog Training One2One and A-ZAnimals, have helped coach thousands of animals using an American training method Mr Cott refers to as "dog whispering". Their other stars include Andrex puppies, the Dulux dog and the Pedigree chum brigade. "The secret is to build up a rapport and teach the dog confidence," said Mr Cott. "Bobby has a natural star quality thrown in for good measure."