I wouldn't normally start one of these, but I have 20 mins to kill on a train, and it's been bugging me all day so here goes.   I'm pretty sure someone in the National party leaked Bridges expenses today - it's the only scenario that makes sense. Let me explain.

Firstly, political expense scandals of this sort are a joke. I see absolutely no issue with the level of expenditure for the role of an opposition leader (particularly a new one). It's barely a rounding error, and if you compared the travel costs for a senior person in the private sector who needed to so similar amounts of travel for their job, it would be a multiple. I've seen nothing to suggest any rorting (which would be cause for a scandal). Government travel is generally pretty frugal.

But there are two key questions that need to be answered. 1) What motive is there to leak the info and 2) who had access to it.

I see motives on both sides. With National polling at 45%, while not enough to govern if those numbers held to the next election, the number poses a serious threat to the re-election of a Labour led government. Harming that number buys some wiggle room. On the other side, Bridges is not a well liked leader, it seems both within some of his own party and the public generally. Yet in spite of this, National still polls at 45%. If you are an aspiring leader (Collins, for example), now is a great time to make a solid hit on the person who's job you want. Plenty of time until the next election (and government coalition still seemingly strong), party polling high in spite of an unpopular leader . If the intention is to roll the leader, the sooner the better. I doubt Bridges would go willingly with party polling high, and a knife in the back will likely hurt the party a little bit (as opposed to him stepping down), so a new leader will want a chance to prove themselves before the next election and let the memory of the back stabbing fade rather than risk even a small negative impact by a knifing close to the election.

When it comes to access, it's clear National party members have open access to this information, whereas no-one in the government bar the speaker should. I can't see Mallard leaking, particularly given he's the only official on the other side who everyone knows has the info, but it's possible that someone in the government has access to something they shouldn't. The fact they shouldn't have it gives them good cover, but is a massive risk if they got caught with information they weren't entitled to have - which would result in a far bigger scandal. With so many in National with access, anyone leaking from that side has plenty of other suspects to hide among.

So what makes me so sure it was a National leak? To me, I just can't satisfy that Labour have anywhere near enough to gain, and leaking has bigger risks to them. They're early in their government and their coalition would be re-elected today based on current polls, their leader is immensely popular and its a long way until the next election and a lot can change between now and then. But for National, this seems to me like a golden opportunity to weaken (and ultimately replace) an unpopular leader while doing very minimal and entirely repairable damage.