After Dinner Speakers: Sean Lock, Marc Almond, Billy Crystal

You wouldn't think it to look at him, this well-dressed, well-spoken chap who appears entirely sensible, dependable and plausible. But Sean Lock is as mad as a colander full of gravy. That gap between what you see and what you get adds an extra dimension to what is always going to be a classy act. For while scores of comedians wrap their offbeat observations in a zany, stand-out-in-a-crowd image, Lock just blends in. Yet he can be as odd as the rest, as he considers the origins of cake decorations, the very essence of atmosphere or the possibility of doing his entire hour-long show in the voice of Lester Piggott. It's not the only lesson to be learnt from Lock, who continues to prove himself a ninja mastered of the comedy art.