How prepared should we be for Greece to crash out of the euro?

John Cridland, the leader of the UK's biggest business group the CBI, has told us that if there were to be a sudden deterioration in the eurozone it would be like an 'earthquake' for British firms - potentially very serious but there's not much that can be done to prepare for it.

He said in reality there is not much that individual companies can do, and they're dependent on what is decided in Paris, Berlin and Brussels.

But I've just been filming on one City trading floor, ETX Capital, where they believe the possibility of 'Grexit', Greece leaving, is so strong that being prepared is the only sensible thing to do.

Andrew Edwards, the boss there, showed me how they have recreated the drachma in their trading systems, simulating bank transactions, and currency exchanges. It took five of his staff a week to get the preparations done in case, as he puts it, "we wake up one morning and Greece has gone".

It was surreal to see the drachma listed on the hi-tech screens of the trading floor, taking its place alongside the dollar, the euro, and other currencies from around the world.

You'll be able to see more on it on tonight's ITV News at 10.