Advocate, land-owner and patron of the arts. The son of an Ayrshire church minister, McEwen was educated at the Edinburgh Academy and Trinity Hall, Cambridge. He became a successful advocate in Edinburgh and was noted as a gifted musician and patron of the arts, supporting composers and serving on the Council of the Royal College of Music (1906-26). He bought Bardrochat House (South Ayrshire) and invited his friend Sir Robert Lorimer (1864 - 1929) to extend it in 1906. When he bought Marchmont House in the Borders in 1913, he turned to Lorimer once again for the renovations and, in particular, the creation of a fine music room.
His wife, Mary Dundas, was the subject of a noted painting by Sir John Lavery (1856 - 1941), Mrs McEwen of Marchmont and Bardrochat & Her Daughters, which for a long time hung at Marchmont House.
His son, Sir John Helias Finnie McEwen (1893 - 1962) became a Conservative politician and several of his grand-children have proven to be successful in music, the arts and writing.