1942, Block wrote an all-star revue for the USO to be performed for the growing American Expeditionary Forces in England. Hollywood stars who volunteered to stay in England for two months to perform in the revue included Carole Landis, Kay Francis, Mitzi Mayfair, and Martha Raye. In December, the Office of War Information sent Block to London to prepare radio broadcasts and write jokes for touring American stars who performed for the troops stationed in England. He soon discovered that writing for soldiers, British and American, required a specialized technique and he studied British humor to understand how it differed from American humor both in language and taste. Also, a military audience required unique sensitivities as soldiers did not laugh at subjects such as strikes in wartime industries, shortages endured by civilians, or especially, cheating wives. He also wrote some American-slanted material for British comedian Tommy Trinder. With the BBC Block was then assigned to the staff at the BBC to add American comedic sensibility to the Anglo-American Hour and Yankee Doodle Doo radio programs. Maurice Gorham, BBC executive and journalist who had "seen a lot of Block" during his BBC days, gave his impressions of Block as "a real Broadway type who reminded me of a Damon Runyon character suddenly set down in a Broadcasting House." His contribution to the BBC was once singled out by the North American Representative of the BBC, Lindsay Wellington, to dispute Associated Press accusations of excessive British censorship. In a December 6, 1943 letter to the New York Times he wrote, "Nor would it have been possible for Hal Block, American scriptwriter, to write the highly popular London-produced program for combined U.S. and British soldier audiences Yankee Doodle Doo." Block made use of his Broadway experience in musical comedy. Block and UPI correspondent and lyricist Bob Musel wrote the popular song The U.S.A. By Day And The R.A.F. By Night for the Eighth Air Force show. The song has been called "the most entertaining song about the war in Europe." The song was unique in taking the approach of praising US and British airmen indirectly by focusing on the horrified laments of members of the Nazi High Command. With a sardonic tone, it featured everyone from Hitler to Rommel bemoaning the effects of the Allied bombing. On one occasion, Block sang the song over BBC radio and when trying to leave the building