Brown writes: "...the ECB is right to consider a symmetrical inflation target and greater transparency. And it is by reasserting the intergovernmental basis of the Stability and Growth Pact – member states answerable to their electorates on tax and fiscal issues – that we will gain support for the medium term fiscal rules best suited to a global economy, rules that take account of the economic cycle, investment needs and debt sustainability"
You ask: "Could it be that to admit the full scale of the EU federal project would be to undermine his position on the euro, that the issue is solely about economics and that therefore he alone has to be the gatekeeper of the decision on a referendum?"
You could be right about Brown and Blair. But why should we assume that Brown wasn't aware of French and German disregard for their Countries pledges to the other Euro members? Or that Brown wasn't aware of the systemic corruption within EuroStat and the ECB, after the Portuguese admitted they'd had help from Brussels obscuring their budgetary violations?? Or that Brown, like Blair, Clinton, Bush, and 99% of political animals is being sincere in stating his position regarding both joining the Euro and Britains entry into the EU as a 'first tier" member? After all, in hindsight the conditions Brown has set for Britains Euro membership look calculated to say, "yes. When XYZ" in a manner certain to allow him to have his "Euro cake and eat it too". For saying "When XYZ" sounds a lot to an outsider like saying "When pigs sprout wings and fly". So why should a Politician, which Brown most certainly IS, critique the federal project when he can safely establish economic tests that are enough in themselves to insure neither he or his Party will be held accountable for French and German duplicity, and that the UK will never adopt that silly EU Constitution.
Imagine Brown saying in late 2004: "Oh well, we'd hoped the others would play nice, but now that it's clear that they're not, Britain's got to work with those Nations within the EU that participated sincerely to build a Europe that protects against the types of abuses that undermined the last attempt."
This process is exactly what the United States when through in progressing from the Articles of Confederation to the US Constitutional Republic. The Anti-Federalists had their way with the Articles, and then had their hats handed to them with The Federalist papers.
http://www.founding.com/library/lbody.cfm?parent=53
"Or that the logic of the proper opposition to the constitution and euro-federalism is to leave the EU altogether?"
I think Gordon Brown and Tony Blair would rather be the EU's "Publius" (Hamilton, Jay, or Madison), than either Jefferson or Adams. The EU will never work if based on "The Rights of Man", rather than on Locke's 'Second Treatesie.." crossed with "Common Sense". New Labour came to power by learning from the New Democrats, and I think it's a safe bet that Gordon Brown is better educated regarding Anglo-American political history than either the Tories or Old Labour or anyone on the continent.