Judging from the brochure (a small A6 card) they would appear to have been made c.1975 by Chance. Following their closure in 1981 I don't know whether Fiesta Glass continued making them, but think not.
They were designed by Jay Lin of Stourbridge (gained from a different source), but there's nothing else on the brochure apart from a black and white photo on the reverse giving the Design Nos. (1 to 6).
But another thing to look out for in future is the box design; a blue background with yellow star design. You can see what appears to be the box peeking out at the top-right corner.
I would also say that if you
haven't seen them before, I'd guess not many were made