The Political Compass test has been around for a few years now. The idea behind it is that you tell them whether you agree or disagree with some statements, and it tells you how you rank on left/right economic scale and authoritarian/libertarian social scale.
The people who run it have put in examples of real life politicians, so that people who take the test can compare themselves. Here's an example from Labourhome about 'omg look how right-wing Labour are'.
As a quick experiment, I did the test, giving the answers that reflect the best guess about what Gordon Brown or the majority of his colleagues would think. And it came up with results of slightly left of centre economically (-1) and slightly more libertarian than authoritarian (-2.7). Which makes more sense to me then the rankings that they gave.
So I think what the people who run Political Compass have done is that rather than use their the same methodology which generates scores for the people who use it to allocate where politicians are placed, they've fixed it such that nearly everyone who takes their test is much more leftie on economic grounds and more libertarian than the main political parties. Which is kind of clever and I approve of on general propagandist grounds , but just another reason not to take it too seriously.