The Chancellor has opened the euro debate. Now let the voters give their opinions

The Chancellor of the Exchequer should be congratulated on clarifying his five tests for adopting the euro.

The Independent has always taken the view that the tests are unnecessary. It is worth recalling that they were only invented after the death of John Smith – a leader who took a straightforward position on matters European – in order to keep Labour's options open.

Until then, Mr Smith's view was that the criteria enshrined in the Maastricht Treaty were sufficient to decide a currency's suitability to join, once the political decision had been made. His view was and continues to be right. Britain has satisfied the Maastricht criteria since before the launch of the single currency. Fortuitously, the pound-euro exchange rate is now equivalent to the famous level of DM2.95, which was not sustainable 10 years ago, when our interest rates were out of kilter with Germany's, but is now.

What matters, then, is making the decision. That depends on the British people's assent to the proposition that their country should be a leading player in an expanded European Union. But it is a decision that rests firmly on a foundation of economics. Given that support for the European project has always been lower in Britain than in most other EU countries, the only way in which a referendum can be won is if the British electorate believe that scrapping the pound will make them richer.

That is not a superficial decision into which people can be tricked by smoke, mirrors and the dark arts of spin. It helps if the euro is perceived as a strong currency rather than a basket case. But the only hope this presentation-led Government has of persuading people, therefore, is to make its assessment of the costs and benefits of joining as rigorous and as objective as it can while being committed in principle on one side of the argument.

To his credit, Gordon Brown has applied himself to this task with a high seriousness. His elaboration of the five tests, in his Mansion House speech on Wednesday night, was not window dressing, as he and the Prime Minister fairly insist. But the closer they are examined, the more people will realise that they are not tests at all. They are in fact five headings under which the costs and benefits of joining can be systematically assessed. And in each case it is now clearer than ever that the "test" will best be met by joining the euro as soon as possible.

The first and most important test is of convergence. Inflation and interest rates have roughly converged, but that is more likely to be "sustainable and durable", in Mr Brown's words, if Britain becomes part of the euro area.

The second concerns the flexibility to withstand regional economic shocks. But British markets are already more flexible than those in the euro area, and the one change Mr Brown mentioned which might make them more so, greater mobility of labour, would be promoted by adopting the euro.

Then there is inward investment – Britain would have more of it inside the euro area. Protecting the City of London's pre-eminence as a financial centre – easier inside. Jobs – more secure inside.

The Treasury's famous assessment will be important in quantifying the likely benefits for growth, stability and employment, and in putting into perspective the negatives, from the essentially cultural dislocation of conversion to the stresses caused by our different housing and pensions markets. But there are no "tests" to be passed or failed, only a net benefit which is already, in this newspaper's view, "clear and unambiguous".

The Chancellor's Mansion House speech was a welcome opening-up of this debate, of the kind which should have happened years ago. Now he and the Prime Minister must have the courage to take it to the people for a decision next year.