THE Tories may have found it - the one idea that can put what has become known as 'clear blue water' between themselves and Labour. For months the problem has been to find a real distinction between themselves and Tony Blair's new model Labour Party. The issue that might succeed in doing so is more than 20 years old and goes by the dreadful word 'devolution' - the transfer of power to separate assemblies in Scotland and Wales, and indeed the English regions. All away from Westminster. Mr Blair believes that only by tackling constitutional issues can he really make Britain fit for the 21st century. By contrast Mr Major knows that whatever the problems of trying to sell economic recovery he has been handed a gift by his opponent, an easy way to work on Labour weaknesses and divisions. The issue is also a godsend for Mr Major because he can concentrate on his charge that Labour has plans which would lead to the break-up of Britain, a nice diversion from other matters. Mr Blair has walked into the devolutionist quicksand and there are few ways out. Coming with Labour's own internal embarrassment this week, over whether or not to ditch its historic commitment to nationalisation, the Commons row over devolution on Thursday can have done nothing but cheer up the prime minister. Mr Blair has had to face up to the fact that the Labour core is Scottish - witness John Smith, Gordon Brown, Robin Cook et al. In a recent poll 44 per cent of Scots were in favour of devolution and 38 per cent for independence. Mr Blair feels he needs to tackle the issue for his Scottish constituency, but he risks alienating England. At the heart of it is what is known as the West Lothian question, after Tam Dalyell, the MP who first raised it and who once represented that constituency. The issue is how can a devolved Scotland legislating on its own taxes have its own MPs at Westminster also deciding on the taxes of English folk to the south? The new Blair answer is to have English regional assemblies as well. But then there is no real demand for them in England. The row broke out after Shadow Chancellor Gordon Brown outlined Labour's plans. The party would move housing, health, education and transport away from London ministers. But different parts of Britain would be treated differently, Scotland's assembly would have taxation powers, Wales' would not - and the English assemblies, well nobody seems to know. Enoch Powell was correct when he summed it up the last time round in the 70s: 'There are two alternatives: either union, which I favour, or a sovereign independent state which, if it is the settled and preponderant wish of the Scottish people, must follow. All else is local government.' Both sides have been preparing for the constitutional battle for months. Weeks ago Mr Major was calling Mr Blair's plans some of the 'most dangerous ever put to the people'. It is hard to come stronger than that. The government would oppose these proposals 'lock, stock and barrel', he said. THE argument seems bound to run up to the next election, while Labour refuses to accept that it makes the party an easy target for the Tories. The move will be a winner in Scotland but glib phrases, such as Mr Blair's 'bringing government closer to the people', mean nothing to the English. In England regional assemblies would look like one more heavy-handed attempt to reorganise local government - and create more jobs for the politicians, who most people are tired of hearing from anyway. In European terms Britain is over-centralised and over secret, and strictly Labour may be right when it talks of a democratic deficit and the under-representation which only benefits placemen on quangos. Nonetheless even Labour politicians in the south cannot see any sense in creating regional government in England. Elsewhere in Europe, throughout France and Germany there have been growing moves towards regionalism, indeed German federalism was imposed constitutionally after World War II to deplete the power of the centralised state. The German regions now would not have it any other way, claiming reducing the size of the centre has kept down the costs of government. Britain contains strong nationalist groups too. The issue is fraught with pitfalls and Mr Blair may well regret taking the first step into it.