Steve:
Tavia asked when Channel 4 started. I know it was the first week of
November,
because I still have the poster, but I'm not sure which year, but I'd
guess 1982.
This seems to support my personal take, which is that C4 took over the role of the beeb in purveying drama in the UK over the early-to-mid 80s. As C4 became more popular, the beeb retaliated by going 'downmarket' and producing and also importing ever more soap opera, of ever-decreasing quality, of which EastEnders is just one example. Thus died all hope of serious drama for many years, and televisual sf was buried with it. (I gave up watching television in 1986 for nearly a decade -- it doesn't look like I missed a lot.)
Tavia