The pound has just fallen through the psychologically important €0.90 cents to the pound level, if it were not Greece we would now have £/€ parity.  It is sinking against the dollar as well. Think what a hung parliament and the inevitable political paralysis would mean for deficit reduction.  Markets would go into a tailspin, the cost of borrowing would rise. We would be looking at a Greek tragedy…

UPDATE : Gilt market has opened down as well.   The market has already removed the Triple-A rating on UK government debt.