As ever, the argument would be that the Bank cannot hope to control what is happening across the Channel, or prevent it from darkening the prospects for the UK. But it can do all it can to offset the upward pressure on bank funding costs and the downward effects on confidence.

BBC: Bank of England sets sail with QE3

The most extreme danger would be if Spain and Italy are cut off from international markets and bank depositors across the euro-zone periphery start to empty accounts, fearing their deposits might be next to be redenominated in national currencies.

WSJ: Europe Girds for Greek Exit