If WHCGT reads the earlier threads, it has already been established that this car is British. So, is it Austin-Healey-based?
Yes, I know..... that was a bit of a non-clue if you see what I mean!
To answer your question, it is not Austin-Healey based, it is much smaller than that.
When you said A-H you are in fact quite close.
The car is question is not a 'one-off' but one of a small series built by a man who was very active in a British racing series in the 1980s.