Britain successfully tests its first atomic bomb at the Monte Bello Islands, off the northwest coast of Australia. During World War II, 50 British scientists and engineers worked on the successful U.S. atomic bomb program at Los Alamos, New Mexico. After the war, many of these scientists were enlisted into the secret effort to build an atomic bomb for Britain. Work on the British A-bomb officially began in 1947, and Los Alamos veteran William Penney served as the program head. In February 1952, British Prime Minister Winston Churchill publicly announced the plans to test a British nuclear weapon, and on October 3 a 25-kiloton device–similar to the U.S. atomic bomb dropped on Nagasaki, Japan–was successfully detonated in the hull of the frigate HMS Plym anchored off the Monte Bello Islands. The test made Britain the world’s third atomic power after the United States and the Soviet Union.