He specialises in local and social history and has written books on the history of the Garnock Valley and Doon Valley, including the towns of Beith, Barrmill, Dalmellington, Gateside, Kilbirnie, Patna, and Waterside.
Montgomery was born in Ayrshire at Broadstone Castle, near Beith.
The work so impressed the Secretary of State for War, Leslie Hore-Belisha, that he appointed Beith Director of Public Relations at the War Office.
He currently resides in Beith, North Ayrshire where he is the director of the military history picture library, Cody Images.