Horace Greeley, prolific gatherer of parish gossip, is obviously named after the founder-editor of the New York Tribune, established in 1841 and for a while one of the most important newspapers of the US.
The Actress Selina Griffiths, who plays Alison Charter, is the daughter of Popular TV Actress Annette Crosbie, who portrayed the character Ingrid Strange in the first series of Jonathan Creek in an episode entitled "The House of Monkeys".
The forenames of the female family friend who was traced in the marriage registration records and was in the address book are identical to Renwick's mother's forenames: Winifred May.
At 19:40 Jonathan refers to "Ten Rillington Place" which is a 1971 British crime drama based on the novel of the same name.