The eldest son of Gordon Pirie, of Château de Varennes, France, and Valentine, daughter of Comte J. Rousseau de Labrosse, he was educated at Trinity College, Glenalmond and at Clifton College. He entered the Army in 1897, was extra Aide de Camp to Sir Gerald Graham in Egypt in 1882, was mentioned in despatches in 1882 and 1885, was ADC to the Governor of Ceylon in 1890–1893, and served in South Africa during the Second Boer War in 1899–1900.
He was an unsuccessful Liberal candidate for West Renfrewshire at the 1895 general election and was elected as Member of Parliament for Aberdeen North at an 1896 by-election, holding the seat until the 1918 general election when he lost to the Labour candidate.
He served in World War I, during which he was promoted to the rank of Lieutenant-Colonel, awarded the OBE, and again mentioned in despatches. He was appointed an Officer of the Greek Order of the Redeemer and the Serbian Order of the White Eagle.
- Leigh Rayment's Historical List of MPs – Constituencies beginning with "A" (part 1)
- "Clifton College Register" Muirhead, J.A.O. p45: Bristol; J.W Arrowsmith for Old Cliftonian Society; April, 1948
- Hamish Fraser, W.; Lee, Clive Howard (2000). Aberdeen, 1800-2000: A New History. Dundurn. ISBN 978-1-86232-108-3.
- Hansard 1803–2005: contributions in Parliament by Duncan Pirie
|Parliament of the United Kingdom|
| Member of Parliament for Aberdeen North
1896 – 1918