"If we were deciding to join the euro, we would have a referendum. " Declaration by the Leader of the Labour party and Prime Minister of the United Kingdom , Wednesday 17 October 2007.
(There are, as musicians say, one or two corners). You do not decide to join the Euro, Brown: you decide to apply to join the Euro and, apart from just promising a referendum on a decision to abandon the Pound, presumably using your own criteria for if the UK economy can face (never mind meet) your five tests:
1 Are business cycles and economic structures compatible with Eurozone interest rates on a permanent basis?
2 If problems emerge, is there sufficient flexibility to deal with them?
3 Would joining the euro create better conditions for firms making long-term decisions to invest in Britain?
4 What impact would entry into the euro have on the UK's financial services industry?
5 Would joining the euro promote higher growth, stability and a lasting increase in jobs?
which were total Balls when first set out, but are now, after the monumental mess made in the last 10 years, full of heffalump traps for the unwary but arrogant non-economist; but you might be emboldened to apply.
If you meet the Maastricht criteria, which currently the UK economy does not, then you can be admitted. If not , not.
You need to pull your head in.