"Diagnosis Murder" episode, "Broadcast Blues" has a trainset - the "Doctor... Kolkaa..." one.
But is Dick Van Dyke anyone's idea of Poirot? "Nom d'un nom d'un nom... ah would know zat sil-you-ette anywhere - Mary Poppins!"
Mystery still not solved?
bells, I completely forgot!
fairest-playing detective series ever (except maybe Kenneth Moore's
"Father Brown"), the "Ellery Queen" episode, 'The Adventure
of the Eccentric Engineer' has a train set, too!
A couple of
clips on YouTube but none that show the train in action - it has a tunnel
through the walls of the engineers house and I think he puts little messages to
his family on the carriages.
I have a
good feeling this is the one!