Based on the character, Mr Lahey, that Dunsworth plays on that show is enough to throw this actor in among the best. There have been actors that have portrayed convincing drunks before, but never to the level of comedy that John Dunsworth brings to the character.
Unlike many actors, John Dunsworth is also very approachable. Whether you find him on Facebook or happen to run into him on the street, he's usually more than happy to talk with a fan or two about his craft or his characters. In fact, his stories of the past and his views on his profession give one an insight into his passion and love of the work he does.