Britain's political parties, not to mention its bemused voters, may wish that the tortuous issue of a single European currency would simply go away. Until this weekend that outcome seemed possible. Amid German fears of losing the mark's stability, French difficulties in meeting the requirements of monetary union and British Euro-scepticism, time travel a la Stephen Hawking might seem as likely as sterling's disappearance.

But the weekend meeting of EU finance ministers in Valencia altered the political almanac. It revealed a dogged if perhaps unrealistic determination to create a single currency by 1999. Kenneth Clarke made it absolutely clear that Britain, unlike many other EU nations, will be purged of inflation and public debt, and so economics would not disqualify it from joining a multinational currency.

In short, as soon as 1998, a decision could be needed on whether Britain should combine with a rump of its European partners, probably Germany, France and the Benelux countries, in forming a single currency.

That may horrify John Major: the Conservatives seem unlikely to be able to deliver monetary union. Even if Mr Major favoured the policy, it would split his party just as surely as did the 1846 reform of the Corn Laws. This may explain why Mr Major has focused recently on discussing future relations between EU members inside and outside a Eurocurrency bloc.

What about Labour? As the party's conference opens today in Brighton, polls suggest that Tony Blair is the politician most likely to be prime minister in 1998. During his first year at No 10 he may have to decide whether to seal the pound's demise.

Yet Mr Blair and his party have been almost as agnostic about monetary union as the Government. Tomorrow, Labour will hold its conference debate on Europe and will enthusiastically embrace the European ideal. Yet the leadership will remain deliberately vague about Labour's attitude to monetary union.

This studied ambivalence is understandable. Labour has its own Euro-sceptics. The party's Europhilia has more to do with support for the European Commission's social policies than with sympathy for the strict monetary discipline that currency union demands. Labour's leadership wants to avoid being accused by the Tories of surrendering British sovereignty. Finally, of course, there may indeed be no point in debating the currency issue: given the poor state of the French economy, it may be impossible for it to meet the 1999 deadline. But if France and Germany do achieve their aim, then the economic and political shape of Europe would be transformed. Britain could not simply ignore the creation of such a powerful bloc: this country would almost certainly benefit more from being inside rather than outside it.

Mr Blair can no longer avoid these issues. His insistence on responsible economic policies, consistent with monetary union, deserves praise. But he must now educate his party and the country about a decision that he may have to confront in the first year of a Labour government. If Mr Blair fails to prepare the ground on Europe, he could find himself as powerless in 1998 as Mr Major is today, faced by an unruly party and an electorate starved of informed debate.