Montgomerie was the fifth son of George Montgomerie of Broomlands, Ayrshire, a minor Scottish laird. He trained as a writer to the signet in 1687. He married Penelope Barclay, daughter of Sir Robert Barclay of Perceton, Ayr on 2 February 1689. His second wife, whom he married in September 1696, was Janet Gray, daughter of Thomas Gray, merchant, of Edinburgh. In 1697 he acquired lands at Wrae in Linlithgowshire,
Montgomerie's business failed in 1712–13, and he was pursued by the Treasury over customs funds. He died on 11 March 1725, and was succeeded by his son George.[2]
^Hayton, D. W. (2002). S. Handley (ed.). "Buteshire 1690–1715". The History of Parliament: the House of Commons 1690-1715. Boydell and Brewer. Retrieved 2 May 2015.