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Courtney's first role in the series was alongside the First Doctor, William Hartnell, as Space Security agent Bret Vyon in The Dalek Master Plan, way back in 1965. The character of Colonel (later Brigadier) Lethbridge-Stewart was to first appear in The Web Of Fear, starring the Second Doctor, Patrick Troughton. Subsequently, the Brigadier would appear alongside all the 'classic' Doctors, with the exception of the Sixth, Colin Baker. He was almost killed off in the Sylvester McCoy adventure, Battlefield, but the producer, John Nathan-Turner, decided against it and the Brig got to retire to the country.
Ironically, Morgaine, the villainness in Battlefield- and presumably the most likely candidate for finishing the Brigadier off- was played by Jean Marsh, who had also appeared in The Dalek Master Plan as Bret Vyon's sister, Sara Kingdom. Vyon was executed by Sara, who thought he'd turned traitor. History nearly repeated itself there...
Lethbridge-Stewart was name-checked several times in the revived series, but his character never quite reappeared, although he did make a return appearance in the spin-off The Sarah-Jane Adventures, which starred Elisabeth Sladen as Sarah-Jane Smith, another popular character from the original series.
The Brigadier was a well-loved character, and it's quite touching to note that Courtney's name is trending heavily on the old interweb today, even with the New Zealand earthquake and the upheaval in Libya ongoing. It says a lot about the affection both Courtney and the character he was most famed for were held in. Many fans wrote in to pay tribute to the man, whose reputation seems to have been- like his character- that of a perfect gentleman, and of a truly nice guy.
It's understandable; I, for one, can't help but feel a genuine sense of loss.
One rather nice suggestion I've heard is that the BBC should rebroadcast one of the classic Who adventures featuring the Brigadier- The Daemons, anyone? Inferno?- as a tribute to the actor. If you think that's a good idea, you might want to visit the Beeb's website and inform them.
William Nicholas Stone Courtney, 16.12.1929-22.2.2011
Brigadier Alastair Gordon Lethbridge-Stewart: Stand easy. Parade, fall out.