Ah, it's an Arnott! Miss Daphne Arnott's sports car from the early 1950's. Most photos show the 1955 1100cc model, and that's what this one looks like. It's been called everything from an Arnott-Climax to an Arnott-Lea Francis to "just plain Arnott", and the sports car version pictured here was apparently available from 1954 through 1957.
I have seen this exact picture identified as a "1954 Arnott - Lea Francis", so that's what I'll call it although I'm not sure that is 100% accurate.