Even a partial break-up would be catastrophic for companies throughout the euro zone, and pretty dire elsewhere in Europe's single market.

But for living wills to have this effect, they must move beyond mere contingency planning and towards a partial break-up of Banks' balance-sheets.

Some bankers think it will become a blue-chip stock, as the biggest of the firms created amid the recent break-up and partial privatisation of UES, Russia's former power monopoly.