David Bullen was this week notified that he would face 20 charges in relation to rogue trading that cost the country's largest bank, the National Australia Bank, A$360m (£142m). Nineteen of the allegations say he used his position intentionally or recklessly to gain advantage for himself. The other accuses him of obtaining a financial advantage by deception.

"I assume a case like this could last for at least a year but I'll just go with the flow," he said. "I am not at all nervous."

Mr Bullen was one of four currency option traders in the bank's Melbourne office who allegedly placed large bets against the US dollar which they hid from the bank's accountants.

He said this week he had "not intentionally done anything wrong". He has also published a tell-all book describing himself as part of a group a highly paid and poorly supervised men who took large risks with the bank's money.

After generating £17m profit for the bank in one year, the traders started "smoothing" their losses from one day to another to hide the risks they were taking, he wrote. A graduate trainee eventually raised the alarm.

"It was a source of great amusement between Mark [one of his supervisors] and me in particular how bad the systems and everyone around us were," he wrote. "We could take any risk in any amount we wanted and no one would be any the wiser."

The incident ended the career of chief executive Frank Cicutto, one of Australia's top businessmen, and led the financial regulator to place embarrassing requirements on the bank including "whistle-blowing" procedures.

Mr Bullen and his three colleagues were fired, and he moved to the country and took to promoting Buddhism over the internet.

Earning up to £142,000 for his financial skills while at the bank, Mr Bullen now argues that buying and selling goods is exploitative.

Explaining why a car should have no price, he writes: "The metal was taken from the earth as ore and smelt. The ore is free. The earth doesn't charge for it! ? Laws allow the elite to charge others for what is free." He has been ordered to appear in a Melbourne court on January 25. His three former colleagues, Luke Duffy, Vince Ficarra and Gianni Gray, have not revealed whether they too have been charged.