EU referendum: Why the UK will be left seriously divided whether it votes for Brexit or Remain

Nearly every opinion poll published during the last few days has put Remain and Leave at or very close to 50 per cent each

Britain is likely to look like a seriously divided country by Friday

We could be in for a very long night on Thursday. Nearly every opinion poll published during the last few days has put Remain and Leave at or very close to 50 per cent each. Even polls conducted by phone that until recently painted a much more optimistic picture for Remain have now also been saying that the two sides are very difficult to separate.

Of course, nobody who remembers the polls’ underestimation of Conservative support at the last general election will wish to rely too heavily on their figures. Maybe one side or the other will eventually prove to have a clear lead. But the polls will have to make an even bigger mistake than last year for either side to win comfortably.

As a result, whether it votes to stay in or get out, Britain is likely to look like a seriously divided country by Friday morning.

Younger voters will have voted strongly for Remain, older ones to Leave. Graduates will have backed Remain, those with few education qualifications will have opted for the exit door. Scotland and Northern Ireland are likely to have demonstrated much greater for remaining in the EU than either England or Wales.

Meanwhile, many a Conservative voter – and MP – will have voted against staying in the EU, leaving the party with battle scars that could well prove very difficult to heal.

Equally, however the vote goes, it is unlikely to prove an unalloyed endorsement of either side’s arguments. If the country votes to Remain, it will have done so despite its concerns about the level of immigration. If it votes to Leave it will have done so even though many fear the economic consequences of that choice. The choice may well have been a difficult one as voters weighed up the implications of “free trade” and “freedom of movement.”

But how will we discover what that the choice has proven to be? The count is being conducted and the results announced local authority by local authority. That means that, on the one hand, we will have a separate tally for the small band of 1,500 voters on the Isles of Scilly, and, on the other, just one result for the three quarters of a million or so people registered to vote in Birmingham.

The first information we will get is the turnout in each area. It is widely thought that a higher turnout will favour Remain, but of this there is no guarantee. The demographic differences in turnout in last year’s general election, when 66 per cent participated, were very similar to those in the 2011 referendum on the Alternative Vote when just 42 percent did so.

But a bigger issue is that there will be no previous results with which to compare the early results. We will not be able to say that there has been a “swing” to Remain or to Leave in Sunderland or Swindon. However, the broadcasters have been analysing many thousands of survey responses to estimate which are the local authorities where Remain would be expected to do well and which the ones where Leave are likely to be in the lead.

It is these estimates that will provide the clue to the apparent implications of the early results. If one side or other starts consistently to outperform its expected tally across a wide range of local authorities it should soon become clear which choice Britain has made.

But if, on the other hand, the early results suggest both sides are performing in line with those expectations, we will most likely be facing a long night. Although Sunderland and Swindon are promising to declare by one or so in the morning, most councils expect to take much longer. The pace will only begin to quicken after 2am, while most results are expected between 3am and 5am.

The last few counts may not be finished until shortly before the financial markets are due to open at 8am. If the result does go down to the wire, they may not get much warning of how in the referendum has turned out. And by then they may well, like the rest of us, already be thoroughly exhausted!

John Curtice is Professor of Politics, Strathclyde University