A celebrated engineer, John Rennie was born in East Lothian. After studying at the University of Edinburgh, he worked for the engineering firm of James Watt, before starting his own business. He soon gained famed as a constructor of canals, docks, harbours and bridges. Waterloo and Southwark bridges in London were designed by him. Close to Edinburgh, Musselburgh Bridge is a fine example of his skill, remarkable for the flatness of the roadway carried over a long span. Raeburn painted him twice.