Part of the storyline for this episode was loosely based on Colin Dexter's novel "The Riddle of the Third Mile".
The character of Alexander Reece appears - over 20 years younger, minus a knighthood and played by a different actor - in the pilot episode of Endeavour (2012).
In which Morse reveals that he prefers a fountain pen to a cartridge pen, any pen to a typewriter, and a typewriter to a word processor.
Guest star Barry Foster was well known in the 1970s as the eponymous star of Van der Valk (1972), which had ended its run in 1977. After the success of Inspector Morse, and after Foster's appearance in it, it was decided to revive Van der Valk. Seven more episodes were made, which came out in 1991-92. It's notable that the revival involved changing the format of Van der Valk to be closer to that of Morse, with two-hour episodes which were shot on location entirely on film.
Barry Foster died on Feb 11 2002, and John Thaw died only ten days later on Feb 21 2002.