After an upbringing on a Central Otago sheep run, `Peter' Aitken, as his friends knew him, was educated at Otago Boys' High School and Otago University qualifying at the outbreak of the First World War. Almost immediately he enlisted and served with distinction in Egypt and at Gallipoli very soon after the landing until the evacuation. Thereafter he was in France with the New Zealand Division and for devotion to duty at the Battle of Messines he was awarded the Military Cross.
Towards the end of the War he laid the foundation of his interest in chest diseases, first at the Brompton Hospital and then at the Walton General Hospital. On returning to New Zealand as lieutenant-colonel, he was appointed to command the Cashmere Military Sanatorium. In 1928 he began practice as a consultant physician in Christchurch and soon joined the visiting staff. He remained a member of the War Pensions Appeal Board and became a foundation Fellow of the College, serving on the then Dominion committee in 1945-46.
William Aitken's other great interest was farming and he owned and worked a property near Queenstown. He was a keen fisherman and had the high humour and ready optimism of that ilk. To the end of his life, even through his long final illness, he took a great personal interest in his many devoted patients and his younger colleagues who had trained with him. He was survived by his wife and a son and daughter.