I am sure the main guy is Steven (Stephen?) Berkoff but don't quote me on that....and I think he's a writer rather than an actor....unless you're talking about one of the others, of course....
The host of the face-changing party is indeed Steven Berkoff, who would quite possibly love to be known as a writer and allround Renaaissance Man as well as a hugely challenging and involved actor on stage and screen, but who is best known to most people as an occasionally hammy thesp who turns up in the most unlikely places... Octopussy, Rambo, Under The Cherry Moon, 9 1/2 Weeks Part II...