In the opening minutes, as Miss Marple stares in wonderment at the lobby of Bertram's Hotel, the manager is on the phone and says, "It's the Festival of Britain, Mr. Porter," followed by, "Uh, no, I'm afraid Miss Otis regrets she's unable to lunch today." The line is from the 1934 Cole Porter song "Miss Otis Regrets" performed by many artists including Ella Fitzgerald and 'Nat 'King' Cole', and more recently by Bette Midler on the final episode of The Tonight Show Starring Johnny Carson (1962).
Francesca Annis, playing Lady Selina Hazy, played Tuppence Beresford, another female sleuth by Agatha Christie, in Partners in Crime (1983).
Francesa Annis played Sheila Upward in Murder Most Foul (1964 with Margaret Rutherford as Miss Marple)
Mark Heap (hotel manager) and Stephen Mangan (police detective) also played together in Green Wing.