Lincsbodger said:The idea of being in a political party is that you all agree on the same policies
Not necessarily. If you want to be an MP, you might join a party if you broadly agree with a lot of its policies because the only alternative is to stand as an independent and that, in our political system, would put you at a severe disadvantage.
"Labour is a broad church" is an often heard statement. If you agree with the general idea of taking from the rich to help the poor, you will most likely be welcome. You views on non class-based issues might be entirely different. Strictly speaking, it's your constituents' views that matter. Did you bother to ask them what they think about abortion - or blood sports - or magic mushrooms???
So you agree with the core policies of your chosen party. Getting rid of civil servants to pay for a tax cut is a good idea - except that huge numbers of your constituents work for the DVLA. Which way will you vote now?