From 1979: the paperback buy-in to the BBC's proto-X-Files THE OMEGA FACTOR.
I've not read this (which I found in a secondhand book shop) but I have seen a few episodes of the TV show itself (thanks to the DVD box set release) and, although I liked the show and the cast, I found the episodesthemselves hard going and somewhat impenetrable. It did remind me, a little, of the much more recent SEA OF SOULS but I don't think that's an entirely fair comparison.
