May Wedderburn Cannan was born in Oxford on 14th October 1893. Her father, Charles Cannan, was Dean of Trinity College. May took a keen interest in literature and had her first poem published in The Scotsman in 1908.
When she was 18 she joined the Voluntary Aid Detachment. May trained as a nurse and eventually reached the rank of Quartermaster. In 1913 she was instructed by the Home Office to make plans to set up a small hospital of 60 beds if mobilized. However, on the outbreak of the First World War, May had to hand over responsibility to a senior officer and she worked as an auxiliary nurse.
May Wedderburn spent four weeks at Rouen in France, before returning to England where she helped her father run the Clarendon Press. This included publishing material produced by the government's War Propaganda Bureau. She also worked for a short period in Paris for MI5. In 1917 May published a book of poems about the war, In War Time.
May Wedderburn published her third volume of poetry, The House of Hope, in 1923. This inspired a letter from an admirer, Percival James Slater, had been wounded while serving in the Royal Flying Corps. According to Jane Potter: "Although they had met only five times the couple were married on 26 July 1924 at the parish church of St George, Camden Hill, London. They had one son, James Cannan Slater."