Birds of a feather

I came across an old book of Harry Hargreaves cartoons yesterday, and fancy using one or two in a presentation I'm preparing. (Harry was born in 1922 and died in 2004.) It's proving hard to identify who holds the copyright to the ones I want to use, and to find out how I can get permission to use them. It hardly seems criminal showing them once at a one-off presentation with full credit, but it would be nice to be able to go through a simple process. Isn't creative commons great!