The Murder at the Vicarage
Dr Haydock appears in three episodes, but is played by three actors: Robin Soans in "The Body in the Library", Robert Powell in "The Murder at the Vicarage" and Neil Stuke in "The Mirror Crack'd from Side to Side". Jason Rafiel, an old friend of Marple's, was voiced by Herbert Lom (who also made an on-screen appearance as Mr Dufosse in "The Murder at the Vicarage") in "Nemesis" and played by Antony Sher in "A Caribbean Mystery".