Labour's big built in advantage in the UK

From the WSJ:

A ComRes telephone poll of 1,003 adults for ITV and the Independent newspaper, released late Monday, showed the Conservatives with 32%, the Liberal Democrats with 31% and Labour with 28%.

Labour's potential advantage—despite its flagging status in opinion polls—are prompting rivals to jockey for position. Mr. Clegg, for example, has complained of the prospect of unpopular Labour Prime Minister Gordon Brown "squatting" in No. 10 without a voter mandate. In such a scenario, anger could spread from Labour's political rivals to the public, where steam is building to demand serious reforms to one of the world's oldest parliamentary democracies.

Labour owes its ability to hang on despite the weak economy to several advantages. Since Tony Blair's landslide victory in 1997, Labour has an advantage in the number of seats it holds in Parliament that is out of proportion to its share of the popular vote. In the last election in 2005, Labour won 36.2% of the votes but 56.5% of the seats in Parliament. The Conservatives won 33.2% of the votes but only 31.5% of the seats. The Liberal Democrats won almost one in four votes but fewer than one in 10 of the seats.

The result: Labour won three percentage points more of the vote than the Conservatives, but dominated Parliament with 355 seats to the Tories' 197. To overcome that advantage, political analysts estimate that the Conservatives will need to win around six percentage points more of the vote, just to overcome the disparity.

The chief reason for this is that Labour wins seats in Parliament with fewer votes. Labour-heavy Scotland and Wales have more seats compared with their population than Tory-leaning England. Even in England, Conservative constituencies are larger. The average Tory seat held 72,950 voters, and the average Labour seat 66,802 . . .