Brexit Possibilities

It’s often difficulty trying to estimate probabilities, particularly when there are many different potential futures.  Availability bias means we tend to assign a greater weight to the options we’re thinking about, even if they’re actually quite a small sample of the possibility space. Brexit  at the moment lends itself to this, with a large number of options opening up in an increasingly unpredictable landscape.

Complicating matters is that there are a lot of different paths to many of the options. For example, we could leave without a deal as a result of May’s deal being rejected and her deciding to simply leave, or alternatively we could do so after a general election, second referendum and second Leave victory. The same is true for many of the other end states. However, ignoring the path for a moment, there seem to be two main factors that would characterise the final state:

  • Who is Prime Minister
  • What our relationship is with the EU.

It’s worth noting that for Theresa May to no longer be Prime Minister she would need to either lose a leadership challenge (in which case she would be replaced by another Conservative, either a Brexiteer or Remain supporter) or else lose a vote of no confidence in Parliament and the subsequent general election. There do not seem to be feasible scenarios in which Labour is in power but where Jeremy Corbyn is not Prime Minister.

In the grid below I’ve set out the probability I assign to each of 16 options in this probability space. Regarding the deals, ‘May’s Deal’ should be taken to include minor tweaks and variations on the current deal, and ‘No Deal’ to include ‘minimal deal’ scenarios where we agree basic functional matters such aeroplane overflights but nothing substantive on separation or the future trading agreement. ‘Another Deal’ would be likely to be either a Norway option, a Canada option or joining EFTA.

Probabilities sum to 100.


  May’s Deal Another Deal No Deal Remain
Theresa May 16 11 10 3
Conservative Brexiteer 0 10 25 0
Conservative Remainer 0 3 0 7
Jeremy Corbyn 0 2 4 9

Taking some key points from this, you can see that I think the single most likely option for Prime Minister is that May will remain, though I still put this at less than 50%, May is a survivor and could easily stay Prime Minister if she defeats a leadership challenge or wins a vote of no confidence.

I give it about a 1 in 5 chance that we Remain, as well as a 15% chance that Jeremy Corbyn will become Prime Minister – both unlikely, but not exceptionally unlikely, probabilities. And overall leaving with or without a deal seem about equally likely.

Two other points worth mentioning:

  • If May is replaced by another Tory, it seems highly likely that that would be a Brexiteer – and in that case No Deal seems the most likely option. If a Remainer replaces her, it would seem likely that at a minimum we’d have a second referendum and possibly just remain.
  • Leaving under Corbyn. Both Corbyn and McDonnell personally favour leaving the EU, even though they have at times put the position of their party above their personal views. I can imagine them winning an election on the basis that they’d call a second referendum and then giving their MPs freedom to campaign on either side (as Cameron did) with them campaigning to Leave, meaning Leave would likely win. Or Leave might win anyway. Either way, if a second referendum voted Leave I’m sure they’d be happy to take us out.

I’ve deliberately not discussed which options I see as preferable here, and I’d ask others to do the same (we’d had that discussion in the past and I’m sure will do so again in future!). However, I would be interested to know what people think of the odds I’ve put above. Are there any options you see as significantly more or less likely?