Don't forget Dr Francis Simons (later Professor & Sir) a naturalised Brit, I know, who invented Uranium gaseous diffusion separation process one Saturday morning in June 1940 using a tea strainer, a bicycle inner tube and sealing wax. He demonstrated it's practical application by separating H2O vapour from CO2 gas in time for inclusion in Tizards mission to the USA in the autumn of that year. At the time the US had relegated the atomic bomb to a 20year "academic " project at least in part because nobody had figured how to separate the active ingredient. Now although it's generally credited that it was Einstein's letter to Roosevelt which kicked the project to super priority the fact that someone had cracked one of the key show stoppers must have meant something......surely.
Francis went on to pioneer Gaseous Diffusion at
Rhydymwyn Valley in north Wales and latter Oakridge.
The Brit team that cracked the implosion Pu bomb were Chadwick, Tuck, Taylor, Peierls, and Frisch.......uh and Fuchs. They took the job on when it was generally considered to be a dead duck;- It had been offered to the best American guy they had, Teller (well a naturalised American ) who declined, so it went to the British Mission who were at the time "a bit out of place" but keen to show what they could do. What was achieved in a stupidity short timescale was simply astonishing.