As Slovaks joyfully exchanged their crowns for euros yesterday and the euro itself reached its 10th birthday, the slow-burning question of whether Britain should join the eurozone received the usual British answer of "probably not and certainly not yet". The question will continue to hover as the financial crisis deepens and the pound slides ever closer to seemingly inevitable parity with the euro.

However, the financial crisis has also strengthened the arguments against giving up monetary independence.

The most powerful is that countries which join the euro give up their rights to set their own interest-rate policy, handing that over to the European Central Bank. Had Britain been a member, from the start, UK interest rates would have been lower than they were until the recent crisis struck. Arguably, that could have exacerbated our housing bubble and resulted in an even bigger crash in house prices - as has happened in Spain and Ireland. The difficulty of managing a currency subject to competing pressures from different national economies has been seen as the euro's potentially fatal flaw, but its strength during the current crisis has prompted the previously sceptical Denmark to consider joining, while Iceland sees the possibility of being in the eurozone as a remedy for its own recent economic ills.

Hints from Jose Manuel Barroso, president of the European Commission, that the UK was "closer than ever" to joining the euro and that the "people who matter" in British politics were contemplating giving up the pound, are based on nothing more substantial than the Business Secretary, Lord Mandelson, saying it would be in Britain's "long-term interest" to join the euro. With the political calculations as important as the economic ones, that remains a considerable way off. Gordon Brown appears as committed as ever to his famous five tests: convergence of interest rates, the impact on financial services, the need for market flexibility, the effect on growth, stability and jobs, and how it would affect investment.

Renewed speculation about joining has been fuelled by assumptions that these tests have now been overtaken by events as much as by the convergence of the currencies. As a poll for the BBC found more than 70% of people opposed to Britain joining the euro (on which Labour has promised a referendum), politicians of all parties have proved more mindful of public opinion than keen to further the debate. Europe Minister Caroline Flint responded that changing the currency was "not a solution" to tackling the financial instability, while shadow Foreign Secretary William Hague boldly insisted that the Tories, under the current leadership, would never take Britain into the euro. A wider debate is needed which takes account of the changing global economic climate as well as populist politics, not least because, after 10 years, the euro has demonstrated a greater resilience than many predicted. Its next test will be how it fares as it absorbs more members from eastern Europe.