Sir Campbell Stuart,K.B.E. (Knight Commander of the Order of the British Empire) joined the CEF in early 1914 as a young subaltern in the 199th Battalion Duchess of Connaught's Own Irish Rangers,of Montreal,Quebec,Canada. Here's a link on this unit.
He was later asked to the served under Lord Northcliffe in New York & Washington,USA as Lieutenant-Colonel(C.E.F.) in rank, and his role as a Assistant Military Attache`at the British War Mission-British Embassy. He was still paid by the Government of Canada!
He was later posted to served under Viscount Lord North Cliffe, in London at the former residence of The Marquess of Crewe in Curzon Street. His role as deputy was to organize information/propaganda as well as reading daily reports about the enemy.
He was to later write a book titled: 'Secrets of Crewe House'. I've managed to find a link of this rare book!
He worked with with "The Times" of London newspaper, during the inter-war years. He was asked to serve as Director of Enemy Propaganda from 1938 to 1940 at Electra House, (Department EH) which was secretly funded by "SIS" for propaganda purposes! On September 3rd 1939, the organization along with Royal Air Force were thinking of dropped propaganda leaflets about 6 million of them over western Germany at the start of the war. Sir Campbell Stuart worked closely with British Actor Noel Coward, who was his representative of the Anglo-French Propaganda Council in Paris,France at the start of the war, and later became good friends.
He later was asked to be Chairman of the Imperial Communications Advisory Committee, and on 17th August 1940, he asked to set down and just devote himself to Imperial Communications for the remainder of the war.