Leading Article: Mr Blair's awfully big adventure - but where is he going?

IT WOULD not only be churlish but also misguided for those living in the largest segment of the United Kingdom not to share in the excitement of the momentous events taking place in Scotland and Wales today. By 10pm tonight the Scottish and Welsh people will have joined those in Northern Ireland (still awaiting the all-too-elusive inter-party agreement required for their own, already elected, devolved parliament to take effect) in a democratic adventure which will leave a large measure of control over domestic affairs in their own hands. This is the first decisive step in a political reshaping of Britain. The only thing that can be said with any certainty about its final outcome is that no one knows what it will be.

In large part, that uncertainty is the Prime Minister's fault. Perhaps the biggest claim Tony Blair has to radicalism is the seismic constitutional change that he is bringing about. Mr Blair's willingness to practise in Britain what he preaches in Europe, namely that power should be devolved to the smallest national unit willing and able to exercise it, is a commendable modernisation which we have long supported. But it will have far-reaching and unpredictable consequences and Mr Blair has so far been notably unwilling to say much about how he sees them developing. There may be nothing wrong with a peculiarly British programme of piecemeal, asymmetrical reform. But Mr Blair, as the architect of such fundamental changes to the governance of this country, needs to start explaining where he expects it all to end.

In what has been, particularly in Scotland, a lively and interesting campaign, there have been lessons for all the parties. Labour will almost certainly discover that, having introduced a proportional voting system, it will not be ruling on its own. A Liberal Democrat-Labour coalition, the likeliest result in Scotland, will be an excellent experiment in pluralism and test of the so-called new politics; it will also be healthy for a Labour Party whose unchallenged hegemony in Scotland allowed it to become fossilised, arrogant and occasionally downright corrupt.

The limited advances expected by the Liberal Democrats will show that PR is not quite the magic wand for transforming their fortunes they have sometimes fondly imagined. The nationalists have discovered a little more about the realities of politics; they may also have finally understood that, even in Scotland, voters are reluctant to opt for higher taxes.

And for William Hague, a welcome revival of Tory fortunes under the capable David McLetchie would be doubled-edged, because it would demonstrate that a gentler, mildly pro-European kind of post-Thatcherite Conservatism may do rather better than the kind he and most of his Shadow Cabinet hanker after.

But the consequences are far more profound than a few transient effects on the UK parties. And they do not just affect the Scots and Welsh. English politics is likely to be affected rather more quickly than most of the English yet realise. To take a single example: if Donald Dewar is forced by the parliament to abandon university tuition fees it will call into question the sustainability of the tuition-fees, policy in England, since Scottish universities would instantly enjoy a competitive advantage.

The London mayoral elections are bound to throw up some sharp questions about why per capita spending on a now relatively prosperous Scotland should be 32 per cent higher than in England. And the English will gradually start to ask what their Scottish colleagues at Westminster are doing voting on English health policy when they do not do so on Scottish health policy.

These problems may not be insuperable. But they are bound to impose strains on the union which if unchecked will stimulate a desire for separation on both sides of the border. We are relaxed about that prospect. But we recognise that this is neither what Mr Blair nor - at least at present - a majority of Scots want. But if Mr Blair is serious in seeing devolution as the means of protecting the union then he will need to show how he intends it should achieve that end. Even if the SNP does not live up to its highest expectations today, it is now a potent political force, ready to seize on every slight, financial or otherwise, from London.

And without some form of devolution in England, whether through regional assemblies or an English parliament, English impatience with the democratic privileges of the Scots may in time become as potent a force for separation as Scottish nationalism. It may be too much to say, as Professor David Marquand claims, that Britain is "sleepwalking" to a constitutional revolution it does not understand. But as we set out on a journey into the unknown, it is time for Mr Blair to outline his vision of where he is leading Britain.