The speed with which David Cameron has turned the victory of No into the West Lothian question is not surprising in a man who is both an opportunist and partisan, and who is concerned to protect his own leadership. But Ed Milband is right to resist Cameron’s rushed attempts to exploit promises made to Scotland, which almost certainly need never have been made, to justify legislation that would allow only English MPs to vote on ‘English’ measures (however they might be defined). Such a proposal is wrong for two reasons.

First, it is wrong in principle to introduce such important constitutional changes in a matter of weeks. No better, in fact, than Salmond’s attempts to rush Scotland into independence without any idea how independence might work. Second, such legislation would fundamentally destabilise British government. It could create a situation in which a government that possesses the confidence of the House of Commons might be unable to pass the bulk of its legislation. That is what the Tories want, on the assumption that they would normally make up a majority of English MPs, but it is a hopeless way to run a country. English votes for English legislation could only work politically if Scotland did indeed leave the Union (and probably Wales and Northern Ireland as well). As a matter of political logic, the Tories should have favoured a Scottish Yes vote. You cannot want Scotland to remain within the Union and have English votes for English legislation. The political system is simply too inflexible to allow it.

Scotland’s continued membership of the Union would be compatible with English votes for English legislation only if the House of Commons were elected by some form of proportional representation. That would at least diminish the chances of a situation in which a blocking majority of English MPs was able to render helpless a British government dependent on Scottish MPs. This makes the folly of the Blair and Brown governments in ignoring electoral reform even more obvious. They were warned often enough that all this – English votes for English legislation – was a possibility, but chose the easy way out in the belief that the elections of 1997, 2001 and 2005 were the norm.

Furthermore, the argument that we can have English votes for English legislation rests on the assumption that the Kingdom of England is socially and economically homogeneous. But it is not. It is highly diverse, and its different parts have different needs. If Scottish MPs should not be able to vote on English issues, why should Surrey MPs vote on legislation which would harm, say, Durham and Northumberland (as they regularly do)? In fact, one reason that Parliamentary legislation is not more harmful to the North of England under a Conservative government is that Scottish MPs can vote on English matters. Without them Conservative governments could do their worst with comparative impunity. Miliband is right to insist that if there is to be constitutional reform it should be carefully considered and not just a Tory ramp. As it stands, in the absence of a reform of voting procedures, the present constitutional structure of the United Kingdom is probably the one that works best.