In the 1899-1900 Inter-Colonial Tournament final he scored 70 and 6-39 in the match. Despite this he was originally only selected as a reserve for the 1900 team but gained his place when others dropped out. He was described before the tour as "Twenty-one years of age.
Later in the tour he scored 142 against Surrey and then 5-44 against Liverpool and District. Wisden reported that "Cox bowled well against Derbyshire and Liverpool and District, and was more than once useful as a change. He should develop into a fine all-round cricketer in course of time" and "Cox especially should develop into a really fine batsman, as he is quite young the experience he gained on the tour must in the future be of immense assistance to him".