Shapecraft made alluminium fastbacks which were normally fitted to 26r Elans for track use, these had a rear quarterlight, some were fitted to road cars which did not have the quarterlight and a few even had a Kamm tail with upturned spoiler.
They had faired in headlights of a different pattern from the 26r, some had 26r front bumpers and wings (fenders); some had the faired in lights with (normal) front end. The lights on your yellow car do not look like any of the published photos of Shapecraft that I've seen (they are lower- Shapecraft lights fit above the bumper line, not through it) and I've never heard of a Shapecraft without the fastback.
I think that I have just about every book published about the Elan and many contemporary magazine articles; I'm not saying that your's is not a Shapecraft, but you are bringing something new to the party, as far as I'm aware.
Please tell us more, it's always interesting to hear new stuff.
Cheers,
Pete.