When the axe starts to swing at an investment bank, it helps to have friends in high places. Young bankers who want to build a glittering career should cultivate friendships with influential superiors, according to a recent study of the career paths of successful bankers.

Having an influential mentor can not only propel a banker up the ranks, but also provide invaluable protection when redundancies are on the cards. Picking the right mentor is the key. Investment banks may employ tens of thousands of people, but relatively few have any influence.