Question: What is the name of the British car that debuted at the Earls Court Motor Show, London, on 20 September 1948, from which the floorpan, suspension and steering were utilised for the Riley One-Point-Five?
Sentence (from "Riley One-Point-Five"): The two models were differentiated by nearly 20 hp (15 kW), the Riley having twin SU carburettors giving it the most power at 68 hp (50 kW).
Relevant evidence: No