Barclays was fined a record $450 million last month by U.S. and UK authorities for manipulating the London Interbank Offered Rate, or Libor, the interest rate that underpins transactions worth trillions of dollars worldwide, between 2005 and 2009.  More than a dozen banks are expected to be drawn into the scandal, which is being probed by authorities in North America, Europe and Japan.

Below is the fascinating account of a former bank staff who worked alongside money market traders on just how it all went down:

Going back a step … and in many industries still today, there is this truly working concept which is my word is my bond. And that’s how the City used to function before, a long time ago, and in many things, up until very recently.

This is the basic assumption in the Libor rates … It’s a highly prestigious invitation by the British Bankers’ Association for you to participate and certainly in many banks, in fact, in most banks it was treated with the respect that it was due. In other words, the ones who were lying – cause there is no other word for it – the ones who were lying about the rate at which they had been offered money or were offering money are a few. It was a persistent few and we all knew it.

All we had to do is once they had put their Libor rates in at 11 o’clock, we would look and go ‘Christ, that’s way out of what we had been doing.’ It is a very small group of people in this business, many of whom are on first name terms and know each other by sight and for drinks and you just pick up the phone and say to whoever ‘I see you are offering three-month dollars at x, I’ll have some of those’. And (that person) would then turn around and say ‘I have got none left’. And you knew that his rate was a lie.