...it had a Chevy, first a small-block, later a big-block. The supercharged big-block version had "Rat Motor" lettered on the injector scoop, it is said to be the first time someone called the big-block that. I have yet to see period photos or magazine articles showing any Anglia or Thames gasser with an Oldsmobile engine.
NHRA first allowed those cars to run under a special dispensation, as the wheelbase was shorter than the minimum at that time. Only certain engines were allowed, unsupercharged. The Olds was not one of them. Later on, the wheelbase minimum was changed and bigger/supercharged engines allowed in these cars, but by then the Olds was no longer competitive.
Chassis is all wrong too. The frame rails should be closer to the body, especially where the doors are. On 1:1 Anglia, Thames, and Prefects, the frame forms part of the door sill. Fabricated frames were not yet allowed, at least a portion of the stock one had to be used.
I would suspect that the kit was designed first, and the Critter decals added to the pre-designed kit after getting permission to use the markings of that car (which it didn't have for long).
--Mark