Thomson was then sent to New York City as part of the British delegation to the United Nations Atomic Energy Commission and did not return until late in the year. After he returned, in January 1947, John Cockcroft called a meeting at Harwell to discuss his ideas with a group including Peierls, Moon and Sayers from Birmingham University, Tuck from the Clarendon Laboratory at Oxford University, and Skinner, Frisch, Fuchs, French and Bretscher from Harwell.