But there is something wrong with the vehicle's bill of lading. It is not just the technical difficulty of reconciling the need for "broad proportionality" with the extension of voter choice and the maintenance of a link between MPs and geographical constituencies. That argues straightaway for something not unadjacent to the election method proposed for the Scottish assembly, with its unwanted consequence that electoral reform ends in strengthening the stranglehold of political party when what the public wants is to weaken it.
Our reservations are not about the driver, Lord Jenkins of Hillhead. The objection to the Electoral Reform Commission is that it represents the piecemeal, blinkered and essentially conservative nature of Labour thinking about the British constitution.
Lord Irvine of Lairg, the Lord Chancellor, denies that Labour is piecemeal in its approach. Yet the launch of the Jenkins commission gives telling evidence - for this reason. A rigorous examination of the franchise for the House of Commons is very necessary and Labour, very properly, has promised to lay the results of that think-in before the people in a referendum. It is a time to don our anoraks or at least see Lords Jenkins, Alexander et al don them on our behalf and debate the merits of different system of voting. But jokes about the detailed arithmetic of electoral method only go so far. Method embodies important principles, which speak to deficits in the representativeness of Parliament and dysfunction in its operation.
That is the point - it is Parliament that is lacking legitimacy, that fails to represent the people of the United Kingdom. Parliament contains two houses, let alone adjunct institutions such as the judicial committee of the House of Lords - our Supreme Court in all but name; it contains, still, aspects of the remaining power of the monarchy. Decisions about the future of the monarchy - which Tony Blair seems curiously unwilling to have made in public - can wait. But the House of Commons cannot properly be appraised and reformed in advance of decisions about the future of the Lords. If the House of Lords is to be recreated as a new second law- making chamber its nature and its electoral methods have to be considered alongside the functions and representativeness of the Commons.
That is not just to say that the constitution is a way of describing a political system, the parts of which are interdependent. Parliamentary reform is a single enterprise. A second chamber of Parliament replacing the House of Lords has to be representative if the laws its makes are to command assent. That does not, however, mean all its members have to be elected. Here is a rough sketch. Up to a fifth of the members of a second chamber might be nominated on the basis of agreement between all the major parties. This does not have to be a recipe for blandness: there are many people, in business, in academe, in the professions who are not partisan but would make great candidates for taking part in deliberative government.
In its elective element, the second chamber might, analogously to the US Senate, seek to emphasise unity in diversity; the basis of its franchise might be large (regional) constituencies, ensuring that Scottish or Cornish residents acquired a voice. If so, the weight attached to territorial representativeness in elections to the House of Commons might be reduced.
Trust in the political system - enhancing which is surely one of the aims of the reform enterprise - hinges on participation in, and methods of taking part in a variety of representative bodies, local authorities and the European Parliament included. They might all eventually have different methods of election, alternative votes here, transferable onees there. Electoral pluralism is a virtue in a pluralist and diverse state. But Lord Jenkins has to bear in mind that the Commons and the Lords are twinned institutions. Their reform is urgent but it must go hand in hand.