Equipment Visible: When Turlough is first at the controls of the transmat capsule, the wire leading to the Guardian cube can be seen.
The Brigadier [ inspecting his wrecked car ]: In thirty years of soldiering, I've never encountered such destructive power as I've seen displayed here and now by the British schoolboy!
Filming location: Trent Park, Cockfosters. Trent Place stands in for Brendon School.
Video: Doctor Who: Mawdryn Undead (BBCV 4547) released in November 1992. Released in U.S.A./Canada (Warner Home Video E1204) in February 1994.
Novelisation: Doctor Who - Mawdryn Undead by Peter Grimwade (ISBN 0 426 19393 8) first published by W H Allen in 1983.
This story was originally written with Ian Chesterton in mind for the role of the schoolmaster, but William Russell proved unavailable. After discussions about using Harry Sullivan (Ian Marter) instead, it was finally decided to use retired Brigadier Lethbridge-Stewart. Now, if Russell had been able to return, we wouldn't have this U.N.I.T. dating problem...
When writer Peter Grimwade asked what the alien Turlough was doing on Earth, he was told not to worry about it: it would all be explained later and was therefore another writer's problem. Turlough's heritage is indeed explained in Season 21's Planet of Fire, written by... Peter Grimwade.
First appearance of Mark Strickson as Turlough.
Nicholas Courtney appears as the Brigadier Lethbridge-Stewart for the first time since Season 13's Terror of the Zygons.
Valentine Dyall reprises his role as the Black Guardian from the climax of Season 16's The Armageddon Factor.
This is the first part of the Black Guardian trilogy, which continues through to Enlightenment.