Happily, it's been about 50 years since I read the first three novels, and about 20 years since I started on the sequels (which never did finish, got about halfway through the third sequel book). So my foggy memories of the storyline in the original trilogy shouldn't detract from the TV series.

I recall there was a BBC radio play or a BBC TV series in the 1980s, I heard at least one episode on the radio but never caught it again....