Are Boris Johnson and the Brexiteers about to take back control?

Four reasons why Britain may be heading for Brexit

There was a surge in the value of the Pound yesterday following a series of polls showing that voters are swinging back to Remain. After a week in which the odds of Britain leaving had soared, the betting markets switched back to Remain. Bookies reported that 95% of all bets placed yesterday were on Remain. As a result, bookies currently put the odds of the UK remaining in the UK in excess of 70%.

While the punters and markets may well turn out to be savvy on this, there are several compelling reasons to believe that the overwhelming confidence in a Remain victory is misplaced.

1. The polls are really close.

The chance of a Brexit result is much larger than the betting markets suggest. There were two major polls out yesterday. One for the Telegraph put Remain two points ahead. However, another for the Times, put Leave two points ahead. Overall, the latest poll of polls puts the two sides on 50% each. Even if we assume the polls are accurate (which is a massive if), it would only take a tiny shift towards Leave, for Britain to exit the EU.

2. Leave voters are more motivated

A recent Comres poll found that Leave voters feel much more passionately about their cause than Remain voters do. Overall 44% of Leave voters said they would be delighted at a win for their side, as opposed to just 28% of Remain voters. Similarly, 44% of Leave voters said they would feel disappointed by a Remain vote as opposed to just 33% of Remain voters. In a very close race this enthusiasm gap could be enough to tip the result towards Brexit. Indeed almost all the polls we've seen so far suggest that Leave voters are significantly more likely to head to the polls than Remain voters.

This is partly down to the nature of the two campaigns. As the Remain campaign's final poster today makes clear, the case for staying in the EU has almost entirely been a negative one.

While fear campaigns can work, they don't always. As Zac Goldsmith's recently failed fear-based campaign showed, fear-mongering only takes you so far. In order to win, you also need a positive argument to motivate supporters to the polls. Much has been made about 'project fear' in the Scottish independence campaign. But the unionist campaigns also made a very positive case for keeping Britain together that resonated with Scottish voters. The Remain campaign have not made similar arguments and indeed it's not even clear that such such arguments would find a big audience among voters, if they had.

3. Leave's immigration argument has been more successful than Remain's economic argument

Remain's strongest arguments in this campaign are its warnings that Brexit would cause an economic shock that could cost jobs, increase prices and even push the UK into recession. These are warnings which have been endorsed by an overwhelming majority of economists, politicians, trade unions and international organisations. However, despite this consensus, many voters are simply not convinced. Only around a third of all voters currently say that Britain would definitely be worse off as a result of Brexit, with only around one-in-four saying they would be personally worse off. By contrast, more than half of all voters believe that immigration would fall if we left the EU. Polls suggest this is the main driver for Leave supporters. As the academic Stephen Fisher wrote in a compelling article yesterday, it's very easy to see an anti-immigration majority for Leave. It's much harder to see an economic majority for Remain.

4. Belief in a big swing-back to Remain could be overstated

There has been much talk during this referendum that the polls will inevitably swing back to Remain in the final days and hours off the campaign. This may well prove to be the case. Certainly in previous UK referenda there has been a tendency for the 'status quo' option to outperform polls conducted in the final stages.

It's fair to say that there has been a move in the direction of the status quo over the past week, even if there are some signs from a YouGov poll last night that this swing-back may have stopped. However, just because something has happened before, it doesn't mean it will inevitably happen again. Anyone who covered last year's general election will remember commentators' repeated confident assertion that 'historical rules' showed that governing parties almost never increased their vote in subsequent elections. It didn't quite turn out that way.

As analysis of previous referenda around the world has shown, while there is a tendency for voters to swing back to the status quo, that swing-back is by no means universal, or in many cases even that significant. In fact, according to one study: "The experience of previous referendums suggests that the eventual Remain vote is likely to be higher than that in polls currently, but not by much – just less than 3 percentage points – and the gap between the current polls and the result is only somewhat more likely than not to be positive for Remain rather than negative." There's still a very good chance that Leave-leaning voters will hover at the polling station and back Remain. There's also a significant chance that the opposite will happen instead.

Adam Bienkov is the deputy editor of Politics.co.uk

The opinions in politics.co.uk's Comment and Analysis section are those of the author and are no reflection of the views of the website or its owners