Scots architect, member of a family working as master-masons and architects at least as far back as the beginning of C17. He trained in France and Italy with his brother William (1734–90), met Piranesi, achieved recognition at St Luke's Academy, Rome, and made useful aristocratic contacts. He made some drawings of the Greek temples in Sicily which he allowed Piranesi and Winckelmann to use (1757). Reaching London in 1759, he won the competition to build the new bridge over the Thames at Blackfriars (1760, opened 1769, demolished 1868), with a handsome and economical design employing elliptical arches. Thereafter, bridges and canal works became a significant part of his practice. With Robert Adam and James Wyatt as contemporaries, Mylne found it difficult to become a fashionable country-house architect, but nevertheless designed several houses, including Woodhouse, near Whittington, Salop. (1773–4), which have a refinement and restraint that pre-empt the Neo-Classicism of the 1790s. His interiors have a delicate decorative manner not unlike that of Adam, which may be explained by the fact that he paid Adam's draughtsman, George Richardson, for drawings on occasion. His finest work is arguably at Inveraray, Argyll, Scotland, where he built the elegant Aray (1774–6) and Dubh Loch (1786–7) bridges, the Church (1795–1800), two groups of tenements, Arkland and Relief Land (1774–6), and the arched screen-wall that is such a memorable frontage to Loch Fyne, and many more structures, all of which are pleasingly well mannered. He carried out extensive redecoration of the principal rooms at the Castle (1782–9), having earlier made alterations to Morris's windows (1777). Amongst several memorials he designed is the urn in memory of Sir Hugh Myddelton (c. 1560–1631—projector of the New River to bring fresh water to London) on an island in the New River at Great Amwell, Herts. (1800), perhaps suggested by Rousseau's tomb at Ermenonville.
Colvin (1995);L&C (1973);Oxford Dictionary of National Biography (2004);A. Richardson (1955);Woodley (1999)