William Paterson joined the Prime Minister's staff late in 1939. His grandfather, William Paterson, had been Minister of Customs in the Laurier Cabinet, from 1897 to 1911. King commented: "Glad to hear that young Paterson, grandson of Hon. William Paterson, recently taken on for research work in the office." (Diary, October 15, 1939) A few months later, he wrote: "Young Paterson is [a] man of splendid promise." (Diary, March 27, 1940)
In 1941, Paterson moved to the British Office of Information in New York. He then left this job to sign up for service in the RCAF, and qualified as an Air Force navigator. He was killed in action over the Ruhr district of Germany on December 23, 1944.