I was gardening t'allotment when this came to the pros, so likewise was unable to claim it.
The power unit of Al't'cock in an ABC flat twin, normally fond in the ABC light car, but occasionally used for very light aeroplanes.
As the ABC was renowned for throwing pushrods into the hedges, one hopes there was a suitable modification to make the engine airworthy.
There was an ABC motorcycle so the answer to AlexFrance is uncertain as the engine was probably used for both cars and motorcycles, but which was most common . . .