Some Brit place did a poll:
That’s not a bad list (and yes, the Ford GT40 is a Brit car — designed and prototyped by Ford UK). I would take issue, however, with the omission of the 1960s Rolls-Royce:
…and the equally sumptuous Bentley of the same era (pre-German takeover):
I would also have replaced the Lotus Elan Mark I (below):
…with the Esprit:
I also feel that a lot of the older iconic Brit cars were ignored — like the MG TF:
…and the pre-war (later Jaguar) SS:
Compared to those two, the Lotus Elan is a clown car.
Feel free to agree / disagree or add your own entrants in Comments.