Courtney played the Brigadier in two BBC Radio 4 "Doctor Who" plays set during the Third Doctor's era, "The Paradise of Death" (1993) and "The Ghosts of N-Space" (1996), alongside Pertwee and Elisabeth Sladen as Sarah Jane Smith. For Big Finish, he has played the part of Lethbridge-Stewart in several plays, with "Minuet in Hell" revealing that he played a role in the establishment of the Scottish Parliament and also that he does covert work for the UN as a plausibly deniable agent. He also played an alternate universe version of the Brigadier in the "Doctor Who Unbound" play "Sympathy for the Devil", opposite David Warner as the Doctor and David Tennant (later cast as the Tenth Doctor) as Colonel Brimmecombe-Wood. At the conclusion of "Sympathy", the alternate Brigadier- referred to as 'Alistair'- joins Warner's Doctor as his companion, but after an unspecified amount of time travelling together, they part ways in the later audio "Masters of War", when the two arrive on Skaro and force the Daleks and the Thals to join forces to fight off an invasion by a race known as the Quatch, Alistair remaining once the Quatch are defeated to help the two sides maintain their new truce.