Old Boy Network Meaning

(idiomatic) A presumed unacknowledged system of association between childhood friends (especially those at school or university together), used for mutual assistance or favouritism.

Example: 2007, Tim Weiner, Legacy of Ashes, Penguin 2008, p. 7:
  His hiring and promotion of senior officers rested not on merit but on an old-boy network of connections from Wall Street and the Social Register.