Over on the YouGov website I’ve written about an experiment we did looking at how the votes might fall in the event that the Labour party did split (the tabs are here). As I say in the article, this needs a thousand caveats – in what proportions has Labour split? Which party is the main opposition with all the publicity that implies? Who is the leader of the anti-Corbyn Labour party, and what sort of policies are they following? How did the split happen? Respondents don’t know, so this can only be a straw in the wind.

The important things to take away are these:

One – there is a sizeable chunk of the Labour vote who are brand loyalists, in the event of a split they would keep on voting for Labour, regardless of whether the left has split away or the right has split away. Just as the faction that is left controlling the Labour party will get the party’s property and assets, they’ll also get that base loyalist vote. Looking at this poll, it seems to be about 28% of the current Labour vote (so about 8% of the national vote)

Two – a lot of Labour voters would go with the left if the Corbyn was somehow ousted and his supporters left. A smaller group of current Labour voters would go with the right if they left, but they’d pick up more support from don’t knows, current Lib Dems and so on. A Labour splinter group of either side would start with around-about 13-14% (again, there are a thousand caveats to this, so don’t take that as set in stone).

Three – the sum total of the support which the two rival Labour parties would be slightly more than the current Labour party (between them they’d get about 34%, compared to Labour’s current polling figures that are around or just under 30%). Under a proportional voting system this might be a good thing. Under First Past the Post this would likely be disastrous for them, splitting the Labour vote and allowing the Conservatives (or UKIP, or whoever) to gain more seats from them. Exactly how bad it would be we cannot tell without knowing how their votes would be distributed geographically, whether individual Labour MPs would be able to retain the Labour vote in their own constituencies. It is likely to be pretty nasty though.

Finally, given the purpose of the exercise was to see what proportion of Labour voters would stick with the “Labour brand” in the event of a party split, we were faced with the problem of what to call the splitters in each scenario. We wouldn’t call them the “anti-Corbyn Labour party” or “Corbyn Labour party” or whatever as the whole point is that they would NOT be the Labour party, we had to give them a new made-up name. But what? In the end we tried it out with various different names to try and cancel out any effect from choosing a compelling or duff name – “Momentum”, “People’s Party”, “Moderates”, “Progress”, “Radicals”, “Social Democrats” – none of the names seemed to make much difference, whatever we called it, the splitters got around 13-15%.