A. J. Cronin (19 July 1896–6 January 1981) was a Scottish physician and novelist. His best-known works are Hatter's Castle, The Stars Look Down, The Citadel, The Keys of the Kingdom and The Green Years, all of which were adapted to film. He also created the Dr. Finlay character, the hero of a series of stories that served as the basis for the popular BBC television and radio series entitled Dr. Finlay's Casebook.
Cronin was born at Rosebank Cottage in Cardross, Dunbartonshire, the only child of a Protestant mother, Jessie Cronin (née Montgomerie), and a Catholic father of Irish extraction, Patrick Cronin, and would later write of young men from similarly mixed backgrounds. His paternal grandparents were the proprietors of a public house in Alexandria, West Dunbartonshire. His maternal grandfather, Archibald Montgomerie, was a hatter who owned a shop in Dumbarton. Cronin was not only a precocious student at Dumbarton Academy who won many prizes and writing competitions, but also an excellent athlete and footballer. From an early age, he was an avid golfer, a sport he enjoyed throughout his life, and he loved salmon fishing as well. The family later moved to Yorkhill, Glasgow, where he attended St Aloysius College in the Garnethill area of the city. He played football for the First XI there, an experience he included in one of his last novels, The Minstrel Boy.