His intense performance showed that his eccentric, doddery Doctor was not just an extension of his own character; it was a character Hartnell created.
I know he had a reputation for playing the heavy but I'm unsure about the availability of his movies on DVD in the states. Are there any in particular you (or anyone else) can recommend that are readily available?
I've seen him in The Way Ahead, where he's a no-nonsense sergeant, Brighton Rock, where he's a crook, The Dark Man, where he's a no-nonsense superintendant, and Hell Drivers, where he's a crooked manager.
I think his performance in This Sporting Life was well-regarded, but I've only seen a few seconds of that. Apparently he's in The Mouse that Roared, but I don't remember his part. Apparently he's also in Carry on Sergeant, the first Carry On movie, which I haven't seen and might interest you as the start of a long-running British franchise (which featured a kind of repertory cast of actors and later specialised in broad, smutty humour). You'd have a good shot at finding these three (the first starred Richard Harris and the second Peter Sellers, and the Carry On films are well-remembered in Britain).
He's not really all that prominent in Hell Drivers, but the film is worth seeing for other reasons (Patrick McGoohan plays the chief villain, in an over-the-top style; Sean Connery - not yet a star - has a small part; the film has an unusual plot and stars Stanley Baker).
In The Way Ahead, a wartime film, a group of draftees become a unit. The film stars David Niven. The Dark Man is an OK 50s British suspense film. Brighton Rock stars Richard Attenborough. My recollection is he played a milder character in that one, but I remember the performance less well.
Of the films I've mentioned, only The Mouse that Roared was in colour.
Police boxes can be seen in the film Gideon's Day , starring Jack Hawkins. There's a bit where the lights on top flash to alert the officers on the beat they're wanted.
Although it's a British film, it was directed by John Ford. I don't know you'd guess it, however.