At the time of first viewing, I would have been around 9 years of age, probably too young to see a cinematic release. But I managed to follow the series on TV and was gripped. I'd tried to watch other Quatermass films but they'd never gripped me like this one, set in a ravaged UK with hoardes if wandering planet people and technology close to failing. The acting was excellent, John Mills was an inspired choice for Quatermass with brilliant supporting cast.
Very 1970s SFX, but no worse that Dr Who of the equivalent time period I'd say . Also scarier for a lad of my age to view as well.