Stan and Ollie - who is the English comic?

In this great movie, Who is the English actor who plays the comic, who is supposed to replace Ollie when Ollie is ill (Bernard Delfont tries unsuccessfully to get Stan to work with him, but Stan refuses)? I think the character in the movie is called Billy Cook or something like that. This guy is very familiar from TV drama but I don't know his name. He isn't in any of the cast lists I've looked at, although he has a more important part than several other people in the list.
He has a Northern accent and is of a similar build to Ollie (i.e. heavy!)
I have to know his name!