John Mylne came from a famous family of architects, stone masons and engineers. John himself was principal master-mason in Scotland by 1636. His best known work of architecture is the Tron Church in Edinburgh's High Street. Besides his building activities, he was an active supporter of the Covenanters and served on Edinburgh Town Council during Cromwell's regime. The classical bust in this portrait (which looks unnervingly similar to Mylne himself) may represent Solomon. Unusually, the artist has used a large sheet of copper as the support, rather than canvas or panel.