Patrick Stewart film with naked aliens who turn people into zombies [closed]

Looking for identification for a film I haven't seen in a long, long time (maybe 2 decades ago).

The film is in colour but I remember it being quite dark, and it was made a while ago, maybe in the 70s. It was set during that time in England and featured naked human-looking aliens going around London (or some other British city) turning people into zombie like things.

The only actor I can remember in the film is Patrick Stewart. The only other person I can picture was one of the aliens who was an attractive female who was always naked. I also have vague memories of a large tower of light or a beam of light where the aliens came from or lived in.

The film stood out to me because it was a sci-fi set in England, which was a rare thing at the time I saw it.