They say imitation is the sincerest form of flattery - but in the wonderful world of celebrity impersonators, not all so-called lookalikes are that convincing. Take this young man, above left, who has just won a major George Clooney doppelgänger contest. He may have a certain je ne sais quoi about him, but we won't be mistaking him for the former ER star anytime soon.

With that in mind, we've delved into the murky, and often hilarious, realm of celebrity doubles. Which ones would you be taken in by? Find out in our gallery, below.

Simply click on an image to launch the gallery.

Picture credit: Rex Features

Top 20 dubious celebrity lookalikes