Complex sentence: It was the first Mexican championship title for British Football Club (Mexico City), whose players were almost exclusively Brits and where player-trainer Percy Clifford, centre half-back "Jack" Caldwall and the Hogg brothers were the most prominent characters.
Split into simpler sentences: It was the first Mexican championship title for British Football Club (Mexico City), whose players were almost exclusively British. The player-trainer Percy Clifford, centre half-back "Jack" Caldwall and the Hogg brothers were the most prominent characters.