Scotland is to be offered legislative devolution. This means that statutory responsibility for education will pass from the Secretary of State for Scotland to the new Scottish Parliament. The Scottish Parliament, however, will be constrained in its actions since it will have only a very limited revenue raising power - the power to raise income tax by up to threepence in the pound.

Scottish nationalists claim this will fetter the new parliament. English critics, in contrast, are frightened that the contradictions in devolution, symbolised by the West Lothian question, are so blatant that the unity of the kingdom could be at risk. What is undeniable is that Scottish devolution will create a new locus of political power in Edinburgh. It places a weapon in the hands of the Scots, and no one can predict how it will be used.

The Welsh Senedd will have no legislative powers at all. It will be restricted to executive powers to pass secondary legislation - statutory instruments, orders and the like. Statutory responsibility for education will remain with Westminster.

Britain has past experience of legislative devolution in the form of the Northern Ireland Parliament, Stormont, which lasted from 1920 to 1972. Executive devolution, however, is quite untried and will introduce a wholly new set of governmental relationships into our constitution.

For, while legislative devolution involves a transfer of powers, executive devolution involves a division of powers. It will be possible to ascertain the precise functions of the Scottish Parliament in education simply by inspecting the provisions of the devolution legislation and looking at the statute book. With executive devolution, however, the functions which the Senedd will enjoy depend not only on the provisions of the legislation but also upon the way in which legislation in education is drawn up. For primary legislation can be drawn so as to give either greater or lesser degrees of discretion to the Senedd.

The trouble is that, lacking a public law tradition, there is in Britain no clear dividing line between primary and secondary legislation. There is no general rule determining whether a particular matter falls under primary legislation, in which case it will be retained at Westminster, or secondary legislation, in which case it will be devolved to Cardiff.

Legislative devolution involves a decision as to whether or not to transfer responsibility for a particular function, for example, education. Executive devolution involves the additional decision as to how much responsibility should be transferred. This requires an answer to the prior question of how primary legislation ought to be drafted.

It would be perfectly possible for a future Conservative government, for example, to limit the autonomy of the Welsh Senedd by drafting legislation so as to leave it little scope for independent action. John Major’s government might well have done that so as to prevent the Welsh Senedd from frustrating government policy on, for example, grant-maintained schools. It would have drawn up primary legislation so tightly as to make it impossible for the Senedd to opt out of the policy.

A further difficulty with Welsh devolution is that the majority of the devolved functions will involve the supervision of services delivered by local authorities. This means that policies involving education will have to proceed through three layers of government - central government, the assembly and the local authority. That could easily prove a recipe for delay and stagnation.

Devolution, if it is to prove successful, requires two fundamental changes in our political culture. The first is an acceptance of diversity. There is no point in creating a Scottish Parliament and a Welsh Senedd if these bodies are merely to replicate what Westminster decides. They are being created because it is argued that there is a distinctive Scottish and Welsh nationality which demands expression in distinctive policies.

Suppose, then, that the Scottish Parliament decides not to follow the Dearing recommendations but resolves, in conjunction with Scottish local authorities, to use local authority revenue to continue to pay maintenance and fees. Council Tax will then be higher in Scotland than England. If Scottish voters are prepared to accept this dispensation, has Westminster the right to complain?

Or suppose, peering far into the future, that the Conservatives regain the position they had in 1955 when they won the majority of Scottish parliamentary seats and a majority of the Scottish vote. Suppose that a Conservative-dominated Scottish Parliament decided to reintroduce selection. If Westminster sought to prevent this by restricting the freedom of the Scottish Parliament, it would be destroying the whole rationale of devolution.

The second change in our political culture which devolution requires if it is to be successful is a more consensual style of politics. In Wales, central government, although retaining statutory responsibility for education, will become less well informed about Welsh needs since it will have lost contact with local authorities, such contact being mediated by the Senedd.

The Senedd will be in a better position to appreciate these needs; but because it will have no legislative powers it will have to rely on close co-operation with the Secretary of State for Wales to promote legislation on education. The Secretary of State, of course, may belong to a different party from the majority in the Senedd. Devolution requires there to be co-operative rather than adversarial relationships between these different layers of government.

For at least the last 300 years, our central constitutional principle has been the sovereignty of Parliament. Devolution, if it is successful, will subvert it by introducing another principle into our constitution: power-sharing. It would be the most radical change in our constitutional relationships since the Great Reform Act of 1832.

Vernon Bogdanor is Professor of Government at Oxford University. His book Power and the People: A Guide to Constitutional Reform was recently published by Gollancz.