Wedderburn spent his missionary career in East Manchuria, working in Ashiho (Acheng), near Harbin, Chao Yang Chen and Hailung.

In the spring of 1918, Wedderburn left Manchuria to serve as an officer with the Chinese Labour Corps in northern France. The British Government had called for Chinese-speaking, British subjects to volunteer for the CLC, a non-combatant force of Chinese labourers who worked behind the lines. He was demobilised towards the end of 1919 and returned to Manchuria in 1920.

After the Japanese attack on Pearl Harbour in December 1941, the British and Americans in Manchuria were interned in Harbin. Wedderburn was arrested by the Japanese Military Police, accused of spying, and placed in a public prison in Harbin, where he was to remain for three months. In June 1942, Wedderburn and his wife Sue, along with other missionaries, were taken from Harbin to Japan. They were interned initially in Kobe and then in a camp on the outskirts of Nagasaki, where they witnessed the dropping of the second atomic bomb on 9 August 1945. They were evacuated by the Americans a month later, reaching Scotland, via North America, in late 1945.

His memoirs, written in 1957-1958, focus largely on his life and missionary work in Manchuria from 1909-1942, with breaks for leave and war service. The chronology of the memoir is interspersed with commentary on various aspects of life in Manchuria, including the difficulty of travelling and modes of transport, dealing with bands of robbers, the outbreak of pneumonic plague, and Chinese and Manchu customs and practices. He also comments on the changing political landscape and the impact of the Japanese occupation of Manchuria in 1931. One chapter is devoted to his wartime service, 1918-1919, with the Chinese Labour Corps in northern France.