Near as I can tell, this film is about a British man driving around in a little green Triumph in 1960’s UK. Prominently features lurking in greenery and quietly pushing branches aside. Also, some people have died from “The Crimson Plague”. Here’s the best summary of the storyline:
Several meteors fall in a field in England. Those who approach them are seemingly taken over, and barricade the area from intruders. A scientist is immune to the takeover due to a metal plate in his head. He enlists the assistance of a friend, who must melt down his silver cricket trophies to make a helmet to protect him. They discover that the takeover is benign, as the aliens just want to repair their rocket and return home.