I agree that some recent historians paint a more favourable image of Chamberlain and his role in the Munich Agreement which ceded the Sudetenland to Germany. As a war PM he did not measure up, which led to him resigning in May 1940, just when Britain needed a strong PM most.
Respected polls ranking 20th century British PMs consistently rank him very poorly. His reputation as an appeaser sits poorly with proud Britons who understand right from wrong.
