I was introduced to them when I saw the Granada television adaptation (i.e., originally on the BBC, must have been shown on PBS sometime.) (Gosh, how old could I have been at the time? 14?) Evidently Deighton was not pleased with how it came out and has attempted to surpress release on video or DVD. So it's only available bootlegged, or direct from Granada Television for large amounts of money.
The New York Times didn't think much of it anyway.