old school tie
noun
1- chiefly Brit. a necktie with a characteristic pattern worn by the former pupils of a particular school, especially a public school〈主英〉（尤指公学的）校友领带。
1.1
- used to refer to the group loyalty, mutual assistance, social class, and traditional attitudes associated with people who attended public schools公学校友情谊：
appointments based on social class and the old school tie.
以社会阶层和公学校友情谊为基础的任命。