1) Courtney was the only actor to work with all the original Doctors - albeit Hartnell pre-dated everything UNIT and NC played a space security agent. Also, the Brig met Doctors Six and Eight only in audio plays.
2) The best Brigadier line is, of course:
Context doesn't make it any less amusing. In "The Daemons" the men from UNIT were shooting at a live gargoyle.
3) Talking about "the Daemons" -- which is one of my favourite WHO episodes full stop. It features bad archaeology, strange pagan rituals, a vicar called "Mr Magister" and secret stone space aliens. And a heavy dose of the Wicker Man and creepy locals. If you tightened up the timing a little and submitted an outline to the current Who Production Office, they would totally take it and probably even give you a double parter.
4) The one remaining Courtney role that I haven't mentioned yet is the Evil Double Brigadier in the parallel universe of "Inferno". He wears an eye-patch, which is all the more intriguing given the (Silence Spotting) Eyedrives. And while it's a parallel universe which has completely wrecked its ecosystem to the point of disaster and they want to move into our Dr Who reality; I think it could well be a Silence-infiltrated/control ecological disaster zone. There were big bangs. Muchly.
In other news, the nurse at the doctor's took some of my blood and gave me sound medical advice to eat cake. She remembered my horrible collapsing veins. She was also less than amused that I was having a fasting blood test at 1pm and hadn't eaten anything since 8pm yesterday.
Mr Magister is (of course) another impenetrable and cunning cover for the Master. But you all knew that.