The rear wing looks sunbeam alpine-ish, but nothing else does. My guess is some sort of Ford special, as the wheel trims don't look all that 'racy' to match the fastback style.
The rear sloping headlights remind me of something, but I can't think what...... However, the rear sloping screen pillars and the proximity of the door shut to the rear wheel arch do look similar (but quite difeferent!) to the car in this article: (under the quote)
I've spoken with the owner Mathew, and I think we discussed it here on TNF before, and it seems likely the basis of HIS car's old body was a Speedex Sirocco, but perhaps it was modified (not very well) to look something like the mysterious blue car? maybe someone saw it at a show.
Surely someone will have featured the blue car in an article at the time, it looks a fairly well resolved project to be an amateur special.
Al