In reality, Cameron's tough words are an effort to toss a few chunks of red meat in the direction of his eurosceptics. Cameron will likely receive some assurances from Merkel and Sarkozy that amount to - well, what?
Not much. Arguing or tub-thumping for more special treatment safeguards for the City of London won't return Cameron much of a result. Should the Europeans opt for a 17-state eurozone-only treaty, by-passing the British, he will have no lever left to pull.
Remember too that many Europeans continue to blame the City of London and Anglo Saxon traders for its part in the eurozone crisis. Certainly the City, along with the global international banking community, played a substantial role. But such finger-pointing fails to direct the finger back at European politicians who spent many years racking up debts they were unable to pay back.