Enniskillen, County Fermanagh born right half William Emerson joined Glentoran in 1912. During his time at Glentoran he won the Irish League Championship in 1917 and 1920, and The Irish Cup in 1914, 1917 and 1921 making 285 appearances in the Irish League and scoring 11 goals before joining Burnley for £1,250 in March 1922. He won the first of his four Irish League representative honours in 1914, he had been capped by Ireland in a wartime international in 1918 and his first of 11 international caps won over a four year period was awarded against England at Windsor Park, Belfast in October 1919. He scored in a 2-2 draw against Wales at The Oval, Belfast in February 1920.
He went straight into the Burnley team after his transfer making his Football League debut against Cardiff City, and in his first full season played 34 games as Burnley finished 15th in 1922-23, however he was dropped after the first two games of the new season and re-joined Glentoran in September 1924 winning the Irish League Championship once again with them that season. He subsequently played for Linfield and Dundalk before retiring in 1930.