Well nobody did. And, in any case, it doesn't really work like that.
Cameron put the kibosh on another EU Treaty (or on an amendment of the existing Treaties), as advocated by Frau Merkel, and thus earned her undying enmity. The City of London has apparently been saved from rule by Brussels, but it is only bankers who will care. And in the longer term, the City cannot expect any favours from Europe.
The members of the eurozone (plus assorted hangers-on) will now establish their separate accord, cracking the whip over debts and deficits. But they will have to do it without the overt assistance of EU institutions such as the Commission and the Court of Justice, while the European Central Bank will or will not fulfil a central role. But as yet, the accord has only been agreed in principle; and there are lots of detail to be hammered out (such as who will conduct the assessment of national budgets).
Meanwhile, the chaos in the markets will no doubt continue ...