At about 18:17 Inspector Barnaby refers to the poem by Rudyard Kipling, "Dane-geld", and the famous line, "once you have paid him the Dane-geld/ You never get rid of the Dane". Dane-geld (also spelled Danegeld) was money paid to Vikings and others in the Middle Ages to keep them from raiding England, now what one would call protection money or blackmail.
Julia McKenzie will go on to portray Miss Jane Marple in Agatha Christie's Marple from 2008 to 2013.
Mr. Jocelyn the solicitor is only mentioned by name in this episode and was played by the late Timothy Bateson who appeared in episodes Written in Blood (1998) Death's Shadow (1999) Orchis Fatalis (2005) He died on the 15th September 2009 (age 83)
Polly Hemingway plays Carol Hatchard in this episode. She previously played the role of Bubbles Stockard in episode 4.4, Who Killed Cock Robin? (2001).