Maitland was born at Kirkcudbright, the third son of David Maitland of Cumstoun, Kirkcudbright. He was educated at Marlborough College and Trinity College Cambridge, where he was a member of the Pitt Club. In 1900 Maitland won the Silver Goblets at Henley Royal Regatta with Claude Goldie. He rowed for Cambridge in the Boat Race in 1901.
Maitland was called to the Bar at Inner Temple in July 1905. He spent some time surveying in British Columbia. In the First World War, he was a 2nd lieutenant in the Irish Guards and was mentioned in despatches. He was killed in action at Klein Zillebeke, Flanders.
- "Maitland, Graham Macdowall (MTLT897GM)". A Cambridge Alumni Database. University of Cambridge.
- Fletcher, Walter Morley (2011) . The University Pitt Club: 1835-1935 (First Paperback ed.). Cambridge: Cambridge University Press. p. 93. ISBN 978-1-107-60006-5.
- Henley Royal Regatta Results of Final Races 1839-1939 Archived 9 March 2012 at the Wayback Machine.
- Supplement to the London Gazette, 8 September 1914
- Rudyard Kipling - Irish Guards in the Great War p14