What Diuretic says. Though party boundaries mean little at the moment, you have the centre which is the right of labour, the left of the tories and most of the liberals (though they often seem to oppose both main parties and can show a lot of sense they are essentially a centre party). Then you have the left wing of the labour party, which includes significantly an ever decreasing number of socialists and the right of the tories which I can't say I know too much about.

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Trust me, I'm a socialist!

There's power in a factory,power in the land, power in the hand of the worker. But it all amounts to nothing if together we don't stand, there is power in a union.
The union forever defending our rights, down with the blackleg, workers unite. To our brothers and our sisters in many far off lands, there is power in a union.
Money speaks for money, the devil for his own. - Billy Bragg