• Investment banks have been hit by Libor and foreign exchange scandals
• Traders’ chats show culture of joking about ripping off clients
• Now most major banks have banned mobiles from the trading floor and increased surveillance of emails and instant messages
• Some bankers have left the industry saying ‘this job used to be fun’ 

City bankers have been banned from using their phones at work, swearing in emails and talking to their rivals as part of a wide-ranging crackdown on their behaviour in the wake of recent scandals sweeping the industry, it has emerged.

Institutions desperate to clean up their act after being fined millions for Libor fraud and currency rigging have imposed tough new rules on employees’ behaviour in the office, MailOnline can reveal.

Investment banks have had their reputations damaged by evidence that traders were conniving to make profits by rigging key benchmarks – often losing their clients money…