General Election 2010

We can rationalise this all we wish, but at the end of the day what is important is the actual result in the real word.

We might arrive at the death of 10,000 factory workers due to some legislation under the Conservatives and we might arrive at the death of 10,000 factory workers due to some legislation under New Labour - and there will always be people who argue that this policy (let's suppose a hypothetical reduction in worker safety) came from a different, more benign, place with New Labour and it came from a more nefarious place when put forward by the Conservatives.

New Labour may be a jolly village green kinda religious party (something I don't agree with, but will let that go for now), but the results are what matter, thousands of schools and millions of children handed over to the church, 100,000 of our children in madrassas alone, a Prime Minister who believed he was telepathically communicating with the creator of the universe, taking advice on such issue as embarking on a war in the Middle East.

This argument of 'sure they did this, but it came from a different place' is wasted on me.

I don't think that's the argument he's trying to make (that is, I don't think he's trying to rationalize it, just explain it). I think it's just an attempt to state the reality of the constitution of the parties, and the affect these constitutions are likely to have on policy.

For example (warning, twee as shit example ahead): the Apple Party is likely to be made up of mostly apples and self-hating pears. Therefore, it will have a large number of people who believe in the importance of apples and their beliefs. This unification of beliefs and opinions will make it easier and more likely to have those beliefs and opinions affect policy.

The Fruit Punch Party is likely to have a large number of apples, oranges, pears, pineapples, etc. in it. When they are coming up with policy ideas, the policies which favour/reflect the ideas of apples are less likely to take the lead. Instead, policies which are more open, and allow all the fruits to whatever they want are likely to be more popular (within the party).

You may hate the beliefs of all fruits (racist), so it's lose-lose for you.

What point is being made here ?
It's a point about philosophical origins of the party, and ideological attraction for its members.