My Lords, I rise to support the amendment moved by my noble friend and to express my own gratitude for the atmosphere that is prevailing in the Committee today. What a difference a decent lunch can make.
My noble friend made a very powerful case. I know that there are people on all sides of the Committee who believe that there is a powerful case for a 10 per cent rather than a 5 per cent limit. Perhaps I may provide the noble Lord, Lord Phillips, with an answer to his question about constituencies. Roughly 69 per cent of constituencies that exist at the moment could still exist with a 10 per cent limit; only 36 per cent of them could exist with a 5 per cent limit. Enormous disruption could be avoided if we put 10 per cent into the argument.
We have to think of the origin of the views on size expressed by the Benches opposite in the early stages of the Bill to understand what has gone wrong. I think that the Conservative Party saw on the one hand-I do not blame it for doing so-that constituencies were very unequal, which they are. It saw on the other hand that the electoral system was biased against it, which it is. But in the mind these two became conflated, which I can quite understand, as cause and effect: that unequal constituency size caused the bias in the system.
This is a matter on which a huge volume of work has been done by psephologists. I suppose that I am the only person in this House whose favourite bedside reading is psephology, rather than, for example, Agatha Christie, Dick Francis and the rest. I have gone through, for example, John Curtice's and others' annex to the British General Election of 2010, the work of Lewis Baston and so on. It is perfectly clear from those that size is barely the cause of the bias that exists in the system. Bias there is: the Conservatives need a 3.3 per cent lead over Labour just to get the same number of seats. I do not defend that, and there are other ways set out in this Bill to deal with it. The bias in the system has varied a good deal over time, but I am very pleased to say that it was sharply diminished at the last general election. It was still considerable and still unacceptable, but it was considerably diminished.
However, the bias is not due to size of seats. In fact, the average Labour seat is only 2,000 electors smaller than the average Conservative seat. In England, the difference is roughly half that. It is not size that makes the big difference. One factor, for example, is Welsh representation, which we shall come back to. The main reason for the bias is differential turnout. In Conservative seats, the turnout is 68.4 per cent; in Liberal Democrat seats, it is 67.3 per cent; in Labour seats, it is 61.2 per cent. That means that it takes many fewer electors to elect each Labour MP than it takes to elect each Conservative MP.
Another factor is that voters in seats where neither Labour nor Conservative candidates can win, an awful lot more Tory votes count for nothing in electing an MP than Labour votes-there are 400,000 more of them. Finally, there is the greater willingness of Labour voters to vote tactically, which costs the Tories a number of seats.
I do not want to gild the lily by going on and boring the Committee into the sleep that I enjoy most nights on reading this stuff, but I say to noble Lords that the Bill's proposal to equalise seat size should be taken on its merits. To me, the inequality in the size of seats is also indefensible, but that is not because it biases the system against the Conservatives. It is indefensible because it leads to too great an inequality between voters. It therefore becomes a matter of the degree to which we want to permit that for other sorts of reasons, such as avoiding crossing traditional boundaries, such as the Tamar, and the desire to keep the Isle of Wight separate, and all the things that we know about.
However, there is not any magic about 5 per cent. There is no difference between 5 per cent and 10 per cent in the results of the general election that was held. So let us consider it on its merits; that is, the principal case of maximum equality achievable against the practical case that a little bit of flexibility in the system should be allowed so as to preserve traditional loyalties and to avoid having too great a swing of seats between one general election and another.