Shipbuilding magnate and philanthropist. Lithgow joined his father's business which operated two shipyards in Port Glasgow. When his father died in 1908, Lithgow and his brother, Henry, took over. They expanded the business and made a fortune building warships and merchantmen during the First World War, with Lithgow's becoming one of the best-known names on the Clyde. With the downturn in ship-building in the 1920s, Lithgow was appointed to lead National Shipbuilders Security Ltd, where he became the architect of a scheme to reduce shipbuilding capacity throughout the UK, with the aim of bringing life back to the remaining yards.
Lithgow continued the philanthropic work of his father by greatly improving the social conditions for the people of Port Glasgow. He also funded a hospital and accommodation for orphans and old people. A committed Christian, he also gave a substantial sum to support the Iona community in the 1940s.
Lithgow died at his home, Gleddoch House at Langbank.