Britain was the first country to seriously study the feasibility of nuclear weapons, and made a number of critical conceptual breakthroughs. The first theoretically sound critical mass calculation was made in England by Otto Frisch and Rudolf Peierls in Feb. 1940. Inspired by this finding the MAUD Committee (a code name chosen from the first name of one member's nanny) was founded. Headed by Sir Henry Tizard, from 10 April 1940 to 15 July 1941, this committee worked out the basic principles of both fission bomb design and uranium enrichment by gaseous diffusion. The work done by the MAUD Committee was instrumental in alerting the U.S. (and through espionage, the USSR) to the feasibility of fission weapons in WWII. A high level of cooperation between Britain, the U.S., and Canada continued through the war, formalized by the 1943 Quebec Agreement. Britain sent the "British Mission", a team of first rank scientists to work at Los Alamos. Among the scientists who made this journey were the pioneer of shock wave physics Geoffrey I. Taylor and a protege - William G. Penney. The mission made major contributions to the Manhattan Project, and provided the nucleus for British post-war atomic weapons development effort.