For all the hullaballoo surrounding Johnny Vegas, some critics have still suspected him of being a one-trick pony. The potter's wheel may be dazzling, they argue, but where do you go after that?

Having just one gimmick, however, may not prove a bar to comic longevity. Many comedians have made a whole career out of endlessly recycling the same schtick.

Dame Edna (above), for instance, has kept going for some decades. Lily Savage cannily delivers variations on the theme of the stroppy Scouse fish-wife, and Julian Clary cleverly reworks Carry On-type innuendos. Bob Downe has been offering to the world a naff, one-note daytime TV host for years. And what are Rik Mayall and Ade Edmondson's antics other than ceaselessly repeated, cartoonish bickering? If the gag is good enough, it'll have legs.

Long live the one-joke wonder.