He was born in 1884 in Queen's County in Ireland, but spent most of his career in England. After two years at the Academy of Dramatic Art, Gawthorne began a career on the London stage, eventually running up over twenty years experience there. His debut was in 1906, a walk-on part at His Majesty's Theatre, London. He was featured in the role of Albany Pope, receiving good notices, in the hit musical The Boy in 1917. He also studied singing.
