This blog post will be updated on a regular basis as I list the characters of every Paul Temple serial - and their fate.
It's going to take a while, because although I tried to record every episode, more often than not I failed in that goal, for a variety of reasons. So I only have between 4 and 5 episodes of each serial, and for most of those I don't have the final ep!
So below are spoilers!
Paul Temple and the Van Dyke Affair
The murderer in the Van Dyke Affair is Roger Shelley (Richard Hurndall)
Throughout the episodes Shelley is presented as an effeminate young man who runs a Mother's Help. In Episode 8, Terry Palmer turns out to be Van Dyke's right hand man (who jumps out the window and dies) and Temple talks to Roger Shelley on the train. He says he knows who Shelley is, and Shelley pulls a knife. But before he can kill Paul Temple, Philip Droste and McCall arrive to save the day. Temple leaves the compartment, and Droste and McCall throw Shelley off the train.
Paul Temple and the Alex Affair
The murderer in the Alex Affair is Carl Lathom (Simon Lack)
The girl in brown - who really was following him - was an FBI agent, working with Wilfred Davis, the Welsh traveller who was also an FBI agent (the actor did a good Welsh accent but his American accent sucked).
Dr. Kohima apparently always knew that Carl Latom was Alex, but cooperated with him because he was in love with Mrs. Trevelyan.
Mrs. Trevelyan did Alex' bidding because he was blackmailing her.