When I mentioned it someone pointed out that it's available on Region 1 DVD (it's actually region free but NTSC so the picture quality isn't wonderful); two seem to be fairly expensive, but the third, Deadly Recruits, goes for £3.98 (but see below).
Arrived today, and on the whole it isn't entirely bad - it's a reasonably good dramatisation of Colonel Butler's Wolf; the main change is that the story now focuses more on David Audley, and Colonel Butler has been replaced by a younger character, Nick Hannah, who was apparently introduced so he could be in the entire series. A young Robin Sachs (Ethan Rayne in Buffy) plays Hugh Roskill, but since the character has a broken leg throughout the story he doesn't get to do much.
Faith Audley seems to have a more important role than I remember from the original book - but I haven't read it in several years so may be remembering it wrongly. She's involved in a subplot about some sort of guru I don't remember at all, but I can't seem to find my copy to check. The dynamic between Faith and David Audley seems a little off, though not too badly so. And the pacing is fairly slow. On the whole an interesting attempt, but I don't think I'll bother to get the other two, Cold War Killers (The Labyrinth Makers) and The Alamut Ambush, given this example.
Now the bad news - This kept stopping at one scene so I took it out of the player, intending to clean it, and suddenly realised that it wasn't a professionally manufactured disk; it's DVD-R or similar, with inkjet printed disk and inlay, so probably counterfeit. So now I'll have to complain to the supplier etc...