Whether it’s storming a branch with masks, guns and a getaway car parked in a back alley, or an elaborate plan to penetrate an underground vault, the act of robbing a bank is often romanticised.

But it turns out robbing a bank can be far simpler and less dangerous. The most lucrative way, it seems, is simply to forge invoices. This has been at the heart of some large bank heists in the past few years involving major banks.