Leaked documents allege that some of the world’s biggest banks have allowed $2 trillion worth of suspicious or fraudulent activity to take place – including money laundering for criminal gangs and terrorists. The so-called “FinCEN files” consist of more than two thousand Suspicious Activity Reports or SARs sent by banks to the U.S. Treasury, alerting the authorities to possible criminal activity, from 1999 and 2017. The files were leaked to Buzzfeed and shared with a network of journalists. Henry Ridgwell reports from London.