The vote on Thursday will have a profound effect on British politics, whichever way it goes. A strong vote to remain in the European Union may revive Prime Minister David Cameron’s political fortunes but split the Conservative Party, whereas a strong vote to leave will make it very difficult for Cameron to remain in charge of the Conservatives and his former friend Boris Johnson will be eager for the job.
If the vote is very close, some MPs will remember that in Parliament a referendum is not constitutionally binding, and they may feel they have to disregard a confused message from the people about such an important issue. But even if the margin is anything less than 10-15 per cent neither side will regard the issue as closed and the war will continue.
So what might happen:
Strong vote to Remain
• Cameron will be vindicated and in theory it should be business as usual. He should start seeking EU reform with fellow reformers like Germany, Italy and Poland. He may even be able to take some refugees from Syria without feeling embarrassed.
• But Cameron will be dealing with a furious anti-European wing of the Conservatives who will feel betrayed. Several MPs may defect to Ukip who would be delighted to take them. If more than eight MPs defect, then Cameron loses his majority of 16 and will have to run a minority government.
• His former ally Boris Johnson and Justice Minister Michael Gove have made themselves into the poster boys of the Conservative membership in the constituencies who are vehemently anti-EU. They may want to stay out of office in a troubled government, and build a new position at the head of a new anti-EU group of Conservatives.
Narrow vote Remain or Leave
• Neither side will accept a narrow vote as final. Both sides will continue to fight on, making it hard to resume normal politics. The bitter exchanges and divisions of the 2016 campaign will become the new fault lines of British politics.
• If the vote is very narrow indeed then some MPs will become deeply uncomfortable with making a decision to change the status quo, and they may remind other MPs that Parliament is sovereign and a referendum is not constitutionally binding, especially a confused one.
Strong vote to Leave
• Cameron loses credibility as Prime Minister and Conservative leader. Nonetheless, he has said he will stay on and invoke Article 50 of the Lisbon Treaty under which any member state leaves the European Union.
• Boris Johnson may well feel confident enough to challenge him for the leadership, especially if his charismatic bumbling is backed by the more formidable Michael Gove.
• The pro-EU Conservatives are unlikely to split from the new anti-EU conservatives as they have nowhere to go. But they will feel increasingly furious as events unfold.
• The negotiations to leave the EU will take a long time and are not likely to go well. The happy Brexiteers of 2016 will become increasingly unhappy by 2018 as the lies of their campaign come home to roost and they find that Britain will still have to contribute to the EU budget and accept free movement of people, among many other conditions of continuing to trade with the EU at anything like favourable tariffs. This will give the new Conservative Prime Minister a major headache.
• His (her?) headache will be compounded by a strongly pro-EU Scotland which might refuse to go along with the exit, and seek a new Scots referendum to leave the UK and stay in Europe.
• The Good Friday Agreement in Northern Ireland assumed EU membership on both sides. Without it the deal will look fragile.