Blackie was born in Gateshead and played for Hebden Bridge before joining Stoke.
[1] In August 1921, Blackie and Hebden Bridge teammate A. M. Moncrieff began practicing with the Halifax Northern Union Rugby Football Club and promised to play in a trial game, which caused worry for Hebden Bridge officials, as to whether or not they would still be able to play association football.
[5] The issue was resolved and in October 1921, Blackie made his first appearance in first-class rugby, playing for the Halifax team.
A local newspaper praised him in 1923: "Sidney Blackie, who formerly played several seasons with the Calder Holme Soccer team has had a successful season in the Rugby code, he having appeared several times with the Halifax senior team and regularly with Halifax Reserves.
In general summary of the Halifax Rugby players performances the writer who follows the Halifax teams for a contemporary refers to Blackie thus: Blackie on many occasions has played very cleverly, his chief failing his inclination become lackadaisical.