The base of the toy adds to the mystery showing an unusual logo, a H inside a globe and a model number, 507, unlike other JR21 Thunderbirds toys.
Armed with this information I have searched for the flying saucer many times. The SWORD Moon Prospector, below, always comes to mind but the lights aren't similar really
More convincing is the T in a Circle UFO, seen below, which has a similar shape, dome and edge. The lights could be altered for the JR21 toy I suppose.
What is far clearer though is that a company called SOMA copied JR21 when they created their Space Ship X711, pictured here left.
SOMA's saucer is the same but white and I think I have found the same saucer being used in another guise, the TIGER Ice Crusher from Japan no less! Difficult to date but the SOMA and TIGER items could be contemporaries, maybe the 1970's or 80's. See what you think from the following comparisons and make your own mind up!