Sentence:  ... might conceivably imply that he did not live, as the custom had been for such boys, in the Abbot's own house, but lodged in the town of Winchester and perhaps attended the College as an <WSD>oppidan</WSD>, or townsman. 
Meaning of the word marked with <WSD> tags:  (also Oppidan) A class of student in traditional English public schools such as Eton; opposed to colleger or King's Scholar.