UFO (TV series)
A single season of 26 episodes (including the pilot) was filmed over the course of more than a year; a five-month production break was caused by the closure of MGM-British Studios in Borehamwood, where the show was initially made. Production then moved to Pinewood Studios in Buckinghamshire. "UFO" was first broadcast in the UK and Canada in 1970, and in US syndication over the next two years.
UFO (TV series)
Only two of the alien suits were made, so at no point in the series are more than two of the aliens seen on screen at any one time. In the episode "Ordeal", Paul Foster is carried by two aliens while he is wearing an alien space suit, but one of those two aliens is always off-screen when Foster is on-screen.