In retrospect, barely anyone uses their natural voices in this Cold War-era espionage thriller from Guy Ritchie, based on the 1960s series of the same name, starring the British Henry Cavill as an American CIA operative and the American Armie Hammer as a man assigned to report to British Naval Intelligence Commander Alexander Wavely (Grant), who eventually becomes the head of the titular organization.
If it were not for his unmistakable appearance, you might not have realized that Hugh Grant was in The Man From U.N.C.L.E. based on how expertly he disguises his aforementioned signature voice behind an exaggerated tone in perfect sync with his role.