Born in the West Midlands region of England, he held seats in southern Wales at The Leys, near Monmouth, and Velindre House, in Whitchurch, Cardiff. He assumed management of the Melingriffith Tin Plate Works in Whitchurch at the end of the 18th century. Eventually, he became sole owner of the works, and was directing its management as late as 1838.
He also owned the Pentyrch ironworks.
He was a contemporary of the ironmasters Richard Crawshay and Richard Hill. Blakemore was a magistrate for the counties of Glamorgan, Hereford, Monmouth, and Somerset.
He served as a Deputy Lieutenant of Monmouth, Glamorgan, and Hereford.