I'm about to re-watch Inferno . It's one the best Who serials of all time ., It has shades of Quatermass , The story has everything !
I've started to watch it, on the basis of your recommendation, and of others online who rate it is the best story of the best season of all time. It is a very good season, but I remember being very bored with the story when it was first shown - are they
still drilling into the Earth's core again this week? - it is the last time a seven-episode story was shown, and back then, for an eight-year old, just a week was a long time. It was also the last time that the excellent Caroline John appeared as Liz Shaw, but it has some of the worst
Doctor Who monsters ever - with their blonde, Lion's mane hair, and green skin - almost as bad as the pantomime Loch Ness monster in the Peter Davidson era.
However, I wonder if you actually have the story mixed up with
The Daemons.
Inferno has the Doctor sideslip into an alternative totalitarian universe, not unlike the
Star Trek Mirror Universe, but it doesn't have much that could be said to be "shades of
Quatermass". On the other hand, the
Daemons is the archaeological dig at the village of Devil's End, and the "Chap with the wings! Five rounds rapid" quote! I can see why you might say that was similar to
Quatermass and the Pit. I remember that
The Daemons was a very popular conversation in the school yard, but it wasn't one of my own favourites.
Edit:
Terror of the Autons next. Great stuff!