Will the UK actually get to Brexit?

Being a lifelong California voter has taught me to be deeply skeptical of referendums. My three years of living in the UK has continually exacerbated that skepticism. The "Leave" vote on the Brexit referendum, in which the UK voted to leave the European Union, has shocked markets, caused Prime Minister David Cameron to resign, stirred a major revolt in the main opposition party, led to calls for a reunification of Ireland, threatens to disunite the United Kingdom, and stirred worries about a broader collapse of the European Union. However, I am left wondering how exactly a Brexit might happen.

I’m not talking about who will lead the Tories, the potential for a second referendum, or whether it is possible for Scotland or Northern Ireland to block the process. Rather, I am just counting the votes: 17,410,742 to leave the European Union (51.9 percent of the total), and 16,141,241 voted to remain (48.1 percent).

Cameron, who initiated the referendum and then campaigned against it, described this vote as a "very clear decision to take a different path" in his . Yet one of the lead Leave advocates, Boris Johnson, that "we who agreed with this majority verdict must accept that it was not entirely overwhelming."

My practical concerns arise because the referendum was also merely advisory. Article 50 of the Lisbon Treaty states, "Any Member State may decide to withdraw from the [European] Union in accordance with its own constitutional requirements."

In the UK, the "Queen-in-Parliament" is sovereign, according to constitutional doctrine. If the next prime minister were to make an Article 50 declaration without a vote by Parliament, it could be overruled by judicial review. This means Parliament must still pass a bill in order to trigger Article 50 and begin the process of exiting the European Union. If you are an MP, it is less clear than one might expect what advice this advisory referendum gives you.

Those 17 million Leave votes were added up in nearly 400 local counting areas that do not correspond exactly with the 650 constituencies that elect MPs. The largest counting area was Birmingham, with around 700,000 potential voters, but Birmingham is represented in Parliament with MPs from 10 different constituencies within the city. The lowest population counting area was the Isles of Scilly, with around 1,700 potential voters. They are represented in Parliament by the MP from the St. Ives constituency, which has an additional 65,000 voters in it.

The complex geography of politics in the UK is how the UK Independence Party could get the largest vote share in the election for members of the European Parliament that it advocates leaving yet hold only a single seat in the House of Commons.

Prior to the referendum, 294 of the MPs outside of the Conservative Party had publicly declared their support for "Remain." Given the positions of the Labour, Liberal Democrat, and Scottish National parties, it is extremely unlikely that those MPs would feel pressure from their parties to vote Leave in Parliament. The Conservative Party itself was torn, with 138 MPs declaring for Leave and 185 declaring for Remain (including Cameron, the recently resigned party leader).

Given the existing declarations outside the Conservatives, any new prime minister would need to convince 83.8 percent of the Conservative MPs who voted Remain and all the MPs who did not publicly declare a side to vote in favor of a Brexit in order to pass the bill required for Article 50.

Certainly, some of these Conservative MPs could be coerced to change their stance given the referendum. But with a "not entirely overwhelming" national vote, will the vast majority of Remain Conservatives now be willing to switch sides? Twelve of the counting areas reported a vote with a margin of half a percent above or below the 50/50 line.

Birmingham, with 50.4 percent voting Leave, was one of those close areas. Maybe Andrew Mitchell — the one Conservative MP from Birmingham, Remain supporter, and former government chief whip — will feel pressure, but with a mere 380-vote difference per constituency in his city it might not be enough to whip him over to a vote for Brexit.

Darren Schreiber is a lecturer at the University of Exeter.

This post is part of Mischiefs of Faction, an independent political science blog featuring reflections on the party system. See more Mischiefs of Faction posts here.