A later production team gave some consideration to bringing Harry Sullivan back for a guest appearance in the 1983 story "Mawdryn Undead", part of the programme's twentieth anniversary season. Their first choice was the character of Ian Chesterton, but those plans fell through due to actor William Russell being unavailable. In the end, they decided to use the character of Brigadier Lethbridge-Stewart (played by Nicholas Courtney) instead. Harry is mentioned in the story, however — the Brigadier tells the Fifth Doctor that he was "seconded to NATO" and was last heard of "doing something 'hush-hush' at Porton Down."