old school tie

A social or business network of graduates of a secondary school, college, or university in which the members help each other because of their common bond. Among the sartorial details of the Harry Potter movies were the distinctive striped neckties that represented each house. The ties echoed those worn by students at real-life British boarding schools and universities and at American prep schools and colleges. Many alumni continue to sport the neckwear for the rest of their lives to show their academic heritage and to allow themselves to be recognized by fellow graduates. Small wonder, then, that this feeling of pride and sense of community makes these alumni kindly disposed to their colleagues, willing if not eager to help them find employment or membership and to gain advancement. In that sense, “tie” refers both to the cravat and to the interpersonal relationship. A similar expression, “old boy network,” comes from the British expression for a graduate of certain upper-crust boarding schools: As a graduate of Eton, James Bond was an Eton old boy.