Milo Tindle: There it is! The original blunt instrument, the poker. Right!
Andrew Wyke: Now, steady...
Milo Tindle: Where do you want it?
Andrew Wyke: Don't get carried away. It's not a murder weapon you're talking about, you know!
Milo Tindle: No?
Andrew Wyke: No. We're discussing an object from which I receive, in the classic formula, a glancing blow which will raise a lump, without actually cracking the cranium.
Milo Tindle: Why don't I just keep tapping you lightly on the head with the poker until a lump comes up?

a film with a two-man cast, and the screenplay is shaffer's own.

i'm sure this is all old hat to those who have been with mankiewicz since their tender years, but i have only just watched the 1972 sleuth, and enjoyed it. (the wiki article is all spoilers, by the way, and allow me to recommend watching the thing first).

and in the 2007 film, now, michael caine plays wyke. and harold pinter is doing the screenplay for kenneth branagh. i look forward to watching it, not least because pinter can do marvellous things, and because branagh is a man of very considerable imagination.

i should mention that i have now watched his harry and his benedick, and i do enjoy his shakespeare.
there was also mozart, incidentally, with clean animation-like colours, and stephen fry with words to the english libretto and dialogue.