Probably a kit car, on an L-suffix plate (early 70s?), 2 door notchback coupe style, quite inspired by a Giulia or maybe a Mustang. Big dragon(?) emblem on the grill.
Bright yellow and in North Bristol if that narrows it down.
I was going to say Gilbern too - if you Google them the dragon isn't present on all cars (maybe they fell off, maybe it's a later addition) but it is the first manufacturer that springs to mind when thinking about the Welsh car industry.
