Vernon Dobtcheff had turn down a role in John Huston's Sinful Davey (1969) because the dates clashed with this episode.
This episode was watched by 5.7 million viewers on its original transmission.
On the DVD commentary, Terrance Dicks got his history mixed up by saying - in a response to a question from Frazer Hines - that William Wilberforce was after the American Civil War. In fact, Wilberforce lived from 1759 to 1833 and the American Civil War was from 1861 to 1865.