Aberdeen-based architect. The son of a clothier in the city, Simpson had trained in London and travelled to Italy. He returned to Aberdeen in 1813 to establish a private architectural practice, living at Bon Accord Square.
Along with his rival John Smith (1781 - 1852), Simpson was responsible for shaping much of the 'Granite City'. Together they worked in King Street, but Simpson is noted for work on Aberdeen Music Hall , the city's Union Street, the Old Royal Infirmary, Mechanic's Institute, the Medico-Chirurgical Society building (1818) and several churches, including St. Andrew's Episcopal Cathedral. He was also noted for his work on country houses, including Stracathro (1827) and Letham Grange (1830).