The company "Snugtop", now one of of the larger manufacturers of
camper shells (I have one on the Ford eff one fitty) started out
making fiberglass tops for sports cars - I remember seeing their ads
back in the '70s in C&D and R&T. I recall that they made them for
Triumphs, MGs, and possibly for those odd little cars that come from
the boot-shaped country where the Pope lives.
I don't know when they stopped making the little tops (they still make
one for the Ma Ma Mia Mumu.... sorry I can't bring myself to say it),
but I bet it was at LEAST 15 years ago. A call to the company might
provide some information - they're in Long Beach, CA.
Check this out: http://www.snugtop.com/about_snugtop.htm