This is an incredible, and wonderfully dated, science fiction show from 1970. It originally aired on the ITV network in the UK and was later syndicated for US Broadcast, as well.
UFO is a 1970 British television science fiction series about an alien invasion of Earth, created by Gerry Anderson and Sylvia Anderson with Reg Hill, and produced by the Andersons and Lew Grade’s Century 21 Productions for Grade’s ITC Entertainment company.
UFO first aired in the UK and Canada in 1970 and in US syndication over the next two years (the shows were copyrighted in 1969). In all, 26 episodes, including the pilot, were filmed over the course of more than a year, with a five-month production break caused by the ultimate closure of the MGM-British Studios in Borehamwood, where the show was initially made.
Based on the Wikipedia page and and search results from google, this show has a quite the cult following, and deservedly so. The set design and costumes are amazingly retrofuturistic.