It takes some chutzpah for David Cameron to attack Gordon Brown as a "shameless defender of the old elite". It is Cameron who is attempting to scupper the government's plan to remove the remaining hereditary peers from the House of Lords. It is Cameron who defends Lord Ashcroft's refusal to say whether he is resident in the UK for tax purposes. And it is Cameron who continues to support the old, outmoded, first-past-the-post voting system.

But on one point the Tory leader is right -- we need fewer MPs. Tomorrow the Conservatives will table an amendment to Jack Straw's Constitutional Reform Bill to reduce the size of the Commons by 10 per cent.

The case for reform is clear; India, with a population of 1.2 billion, has 543 MPs, while Britain, with a population of 61 million, has 646. Only China has more MPs, and China's population is 20 times the size of Britain's. As the expenses scandal demonstrated, we need fewer but better MPs. At present, far too many are mere lobby fodder who contribute little to parliamentary debate.

Labour has rejected the Tory proposal out of hand, accusing Cameron of "blatant gerrymandering". The Tory leader hopes to eliminate the anti-Conservative bias in the electoral system by reducing the differences in constituency size.

Tory MPs tend to represent larger constituencies and Labour MPs smaller ones. As a result, in the 2005 election, it took just 26,906 votes on average to elect a Labour candidate, but 44,373 to elect a Conservative one.

Yet research suggests that Cameron's proposal will in fact do little to benefit the Tories. As Professor Michael Thrasher points out:

Labour continues to benefit from electoral size but its real advantage currently stems largely from a better-distributed vote -- it acquires fewer surplus and wasted votes than its rivals. It is also benefiting more than other parties from the general decline in electoral turnout, requiring fewer votes for its victories.

While Tory supporters are likely to turn out to vote wherever they are, Labour supporters are more likely to stay at home if the seat is either safe Labour or safe Tory and, therefore, one in which their vote will be wasted.

The only sure-fire way to eliminate anti-Tory bias in the electoral system is to introduce proportional representation, but the Conservatives' enduring hunger for the sort of majorities delivered by Margaret Thatcher leaves them blind to this point.

Follow the New Statesman team on Twitter.