But whether the cumulative impact of its market rigging was more or less great than UBS's is - I am told - still undetermined.

BBC: Heads may roll at RBS over Libor

Parmalat founder Calisto Tanzi is serving an eight-year sentence on market rigging related to the stunning 2003 collapse of his dairy empire despite his advanced age.

NPR: Knox Case Puts Italian Justice Under Scrutiny

But after the financial crisis they were brought in to fix RBS's investment bank, and the concern is that they did not get to grips with the market rigging that continued on their watch.

BBC: Heads may roll at RBS over Libor

There is no specific criminal offence of rigging the Libor market.

BBC: From profit to prosecution?

Sources in the last Labour government have told me that it was well known at the time that ministers wanted to do everything possible to reduce the cost of credit to help get the economy moving, but have stressed that this was totally different from allegations about the rigging of the market and lying about the Libor rate.

BBC: Banking probe row turns political

It is because the market was opened up to competition after years of inefficiency and price-rigging.

BBC: Q&A: British Energy's crisis