Dennistoun, Glasgow born right half George Key played junior football for Baillieston Rangers in 1897 and Parkhead Juniors in 1898, before stepping up to join Heart of Midlothian in 1899, making his debut that August. With Hearts, Key won the Scottish Cup in 1901 when Hearts beat Celtic 4-3 in the Final, and the following season he was capped for Scotland in a 5-1 victory against Ireland at Grovesnor Park, Belfast, although this proved his only international cap.
After a disagreement with Hearts over financial matters, Key was signed by Chelsea in the 1905 close season for their first season in English football after 8 goals in 96 appearances for The Jambos. The Chelsea manager Jacky Robertson had been an international teammate of Key’s three years earlier. He made his Football League debut at Stockport County in September 1905 and was a regular during his first season as Chelsea narrowly missed out on promotion to the First Division, finishing third. By the time they succeeded the following season, Key was already a fringe player, making only 4 appearances in the campaign, going on to make 17 further appearances over the next two seasons in the First Division. Key left Chelsea in 1909 to re-join Baillieston Rangers having scored twice in 56 appearances for The Pensioners.
His brother William, who played for Queen’s Park and St Mirren, was also a Scotland international.