Britain must have a totally free fiscal hand for the financing and refinancing of government debt and deficit by the Bank of England.
It cannot satisfy the rules which, even without the new pact that it has failed to join, discipline all EU members' fiscal policy (regardless of the use or no of the euro) through the Growth and Stability Pact.
Nor can the the main Coalition Government partner antagonise the City institutions that have so generously funded them in their electoral campaign and current activities.
Of course they could always have continued to go through the motions of looking as if they are following the rules, with small qualifications, , exceptions and delays, and pretexts, as they have been doing up to now, claiming exemptions - euro, internal market, Schengen - although sooner rather than later they would have had to accept squarely that the country is excessively indebted and that the Party is in pawn to its funders.
This might once more have been acceptable or benignly neglected by the EU but it hasn't helped that London-based hedge funds mounted the assault upon Italian bonds. Italy isn't a minor, peripheral member-state of the EU; Merkozy is complemented by Montraghi in the governance of Europe.
This time bluffs have been called and exceptions not allowed.