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Forgive me if you are not a fan of political conspiracy, and on a day like today you don't have to look very far for huge ideological disputes, even if they're not quite yet punch-ups.

Iain Duncan Smith, in what he said was his first interview on Europe in 10 years, has just told me that staying in the EU puts us at increased risk of an appalling attack like the terrorist killings in Paris, while the prime minister was on the TV sofa this morning saying that we are safer in the union.

This is the new, if temporary reality: cabinet ministers disagreeing totally with each other on the record, and in public. Traditionally unthinkable, certainly risky, and difficult to control.

Plenty of disagreements are spilling out into the public domain now. After lots of speculation, Boris Johnson has just declared he'll be campaigning for Britain to leave the EU. But many are still wondering about the motivations that lie behind his decision.

Unless Machiavellian machinations deep in the Conservative party interest you, you probably shouldn't read much further. But believe me, on long days in Westminster, this is the kind of hypothesising that concerns politicians and their teams.

Ready?

Conspiracy One - Michael Gove's decision to go with the Vote Leave campaign was taken to make sure that Chancellor George Osborne will be challenged in the eventual Tory leadership by someone who is a chum, who looks on him favourably, but who would get onto the final ballot (which crucially only has two contenders) as someone who can claim to the party membership which is broadly Eurosceptic, that they fought to leave the EU, even though they were then sadly defeated.

This, so Conspiracy One goes, is why Mr Gove's decision to join Vote Leave has not impressed some true believers in the cause and, in any case, his public image may well not be a benefit to them.

Conspiracy Two - Doing the rounds inside Number 10 and Number 11 (the chancellor's abode) so the theory goes, is that Boris is intent on becoming 'The Man Who Tried'. What? Well, Downing Street has concluded that Mr Johnson is going for Leave precisely because he is confident that they will lose.

This allows him to create the perfect platform for his leadership ambition - campaign for Leave, Remain wins, but Boris manages to then glide onto the leadership ballot as the man who gave it his damnedest, didn't quite pull it off, but can scoop up oodles of votes from the broken-hearted Tory membership, despairing in defeat, but ready to go over the top for their hero.

This kills Mr Gove, or anyone else's chances of opposing Mr Osborne in the final round of the leadership contest.

If you got this far, and feel enlightened by it all, then marvellous. If it seems fanciful, then don't say I didn't warn you!

But with the prime minister having already announced that he's leaving his job before the next election, there is no escaping the fact that the future of the Tory leadership is a factor in both sides' campaigns.