One of the consistent outcomes in my latest round of Brexit Diagrams has been to foresee a General Election as the most likely outcome of the Brexit process. “But a General Election is not an outcome!” has been the common retort from my readers. “Do any of us know how a General Election would go?” has been my normal response to that.

But here, cautiously, and with a bit of prompting from David Hayward and Peter Geoghegan, is the framework of my thinking of how a General Election could work out.

There are three crucial questions to ask.

First, to what extent is Brexit the dominant determinant of voting behaviour?
Second (in light of the first), to what extent do electoral alliances form so as to avoid splitting the pro-Brexit or pro-Remain camps?
Third, how much do traditional party structures (and, more widely, activists on the ground) actually matter if a General Election were held?

Answering the first of these, we do not know the complete extent to which Brexit shapes voting behaviour, but we have some idea – the most interesting polling is YouGov asking Tory Party members about Brexit, and that they would sooner see Brexit delivered than their own party survive, and Lord Ashcroft polling digging into voting motivation after the 23rd May European election, where he finds Tory defectors to the Brexit Party ready to stick to their choice and, to a lower extent, Labour defectors behaving likewise. Yes, that was just a European Parliament election with 37% turnout fought in unusual circumstances, but the percentages for the parties – and especially the weakening of Labour and the Conservatives – has filtered through to Westminster voting intention. Also note the motivation for the vote for each party that Ashcroft has found out – Brexit is number 1 issue for Brexit Party voters and Lib Dem voters, and number 2 for Greens.

The question then is how do the respective parties respond? And can electoral alliances form so as to allow voters to express their Brexit preferences at the ballot box in a General Election? Here there are major questions to answer for both Leavers and Remainers.

On the Leave side, the biggest unanswered question is what does the successor to Theresa May (assuming that person can even govern – but that’s a topic for another time) do about Nigel Farage and the Brexit Party? The assumption from Jeremy Hunt – who has not sounded keen on the idea of an early General Election – is to get on and do Brexit, and hence avoid an election, and then hope that by 2022 the need for the Brexit Party has disappeared.

Although he would never dare express it as such, the strategy for Boris Johnson might well be a different one. Having positioned himself as the harder of the two candidates on the Brexit issue, and having said that Brexit has to happen come what may by 31st October, he will then face defections of MPs (Grieve, Clarke) that will deny him a majority. Going for a General Election might then be his only way forward. And how to win such an election? Unify all the pro-Brexit forces behind the Conservative Party.

Or, in other words, make the Conservative Party the Brexit Party.

How could Johnson do that? Invite Farage to join the Conservatives, put him in the Lords (or even find a safe seat for him?) and promise to make him Brexit Minister after an election, and in return ask him to not run any candidates for the Brexit Party, and to essentially wind up the party.

Farage has said he is open to some sort of alliance, although he also cautioned that he thinks a Tory Prime Minister could not deliver on his side of it.

Of course not all of Farage’s supporters and voters would indeed fall in behind that strategy, but the European Parliament elections showed that Farage himself has considerable power as a leader – he essentially destroyed UKIP and built his own framework movement within a few months. Yes, some Conservative members and a fair few MPs would leave or defect, but whether that really would make a substantive difference depends on what the other side did…

Because there the capacity for a Remain alliance is starting to become clearer, but currently is far from certain. Here the Brecon and Radnorshire by-election is acting as a test case, where Greens and Plaid Cymru have stood aside for the Lib Dems to increase the chances of defeating the incumbent Tory. Trying to replicate that across 500+ seats is going to be one hell of a task, but were the Remain parties faced with a Tory-Brexit-Party alliance, that would be exactly what would have to happen.

And then of course we come to the Labour Party, and the well documented tensions at the top of that party to try to come up with a coherent Brexit position. There would have to be some effort to bind Labour – or at least some of the more explicitly pro-Remain MPs within it – into some sort of Remain alliance. But how to actually go about that, given Labour’s current state of internal dysfunction is a complex task.

So on this issue it is all to play for just now.

You could envisage a Johnson-Farage alliance gaining 55% of the seats based on 40% of the vote at a General Election and then having the numbers to take the UK over the cliff of a No Deal Brexit, their election victory coming at the expense of divided Remain voters and parties, with the Remain vote in England split 3 ways between Lib Dems, Greens and Labour.

Or, conversely, the new Tory leader could revert to the principle of keeping the Tory Party together, and see an alliance with Farage as a step too far. And an alliance for Remain could crystallise, resulting in a majority for Remain parties and MPs that could form a rainbow coalition post-election.

And as if that were all not complicated enough, there is a further unknown in all of this: the capacity for grassroots organising to shape election results. The Brexit Party was supposed to have been able to win the Peterborough by-election on 6 June, but did not. Why? At least in part because the Labour Party mounted a professional ground campaign. And Remain, lest we forget, managed to assemble a million people on the streets of London in March. UK General Elections are still rather low budget and largely activist run. The Brexit Party, like UKIP before it, has no functioning local structures, and the Tories have a measly 160000 members. Up against there would be considerable activist strength of the Remain side.

Were a General Election to be held between now and 31st October it is ridiculously complicated to know what would happen. Every outcome between a No Deal Brexit and a Remain electoral pact that could put the UK on the track towards a Second Referendum are possible outcomes.

After 23rd July, when the outcome of the Tory Leadership election is known, UK politics is going to get very interesting indeed, were it not already interesting enough!