Town and gown

Not just ‘any’ university - Oxford (maybe Cambridge - I went to Oxford). The ‘gown’ refers to academic gowns that all Oxford (maybe Cambridge) students used to wear all the time as their ‘uniform’ as students. (Now only for exams, matriculation, graduation - special events). These gowns were different for undergraduates and graduates, and of course showed that one was a member of the university, not simply a resident of the town of Oxford or Cambridge. Thus it was quite easy to identify drunken brawlers, for example, as ‘townies’ or ‘gownies’ when the police report was given. It’s not an expression used in the US, as far as I know.