old school tie

Từ điển Oxford Advanced Learner 8th

ˌold school ˈtie [old school tie] BrE NAmE noun (BrE)
1. countable a tie worn by former students of a particular school, especially a private one
2. the old school tiesingular used to refer to the fact of men who went to the same private school using their influence to help each other at work or socially, and to the traditional attitudes they share
•Systems based on social class and the old school tie are more common in Britain than in the US.