Second referendum polling explained: Has Britain really changed its mind over Brexit? Support for a second referendum has grown in recent months, while some polling says Remain would now win

The UK has stayed sharply divided in the two years since the vote to leave the EU, with mounting support among some politicians and members of the public for a second referendum.

Part of the justification for a second vote lies in saying lots of the public have changed their mind since voting 52 per cent versus 48 per cent to leave the EU.

But does the evidence support the claim?

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Support for remain versus leave

The most decisive evidence for a change of opinion comes from the widely-respected social research institute NatCen, in a report authored by the UK’s foremost pollster, Professor Sir John Curtice.

The report, published on Wednesday, appears to show a seismic shift in public opinion. Instead of the four-point lead in the real vote, the NatCen polling suggests Remain would take an 18-point lead in a referendum, winning by a landslide 59 per cent to 41 per cent.

Previous polling as part of the same series of studies had shown a Remain lead, but a much smaller one, holding steady over two years at around 53 per cent to 55 per cent.

There are some caveats to this analysis, however. The first is that it’s based on a hypothetical repeat of the referendum with a straightforward remain vs leave outcome – whereas if there was a vote on a final deal, it would likely take a different form, including accepting whatever deal was on the table, and then whatever alternative (no deal or no Brexit) was offered.

The figures are also not quite so stark as they first appear – the research also polled people asking how they voted in the actual 2016 referendum. The sample polled told researchers they voted Remain by 53 per cent to 47 per cent, a considerable diversion from the actual result, suggesting the sample may tend Remain.

As such, the research – in line with other polling, which has generally shifted to Remain – does suggest there has been a statistically significant shift towards Remain, though possibly not quite as large an effect as the headline figures suggest.

Support for a second referendum

Remain beating Leave in the polls for a hypothetical second referendum is a very different thing from saying that a majority of the country would support a second referendum – and polling on that specific question has been quite hit or miss.

There was a substantial milestone reached in July, where a YouGov poll showed for the first time more of the public support a referendum on a final deal than oppose one (42 per cent versus 40 per cent, with 18 per cent saying they don’t know).

This poll definitely represents a long-term shift in opinion – when YouGov first asked the question in April 2017, only 31 per cent were in favour, versus 48 per cent against.

While that clearly represents a real and large change in opinion, support for a second referendum often depends on the wording of the question – meaning campaigners on both sides can often generate polls that will give them the answer they want.

Different people hear different things when they hear “second referendum” or “referendum on a final deal” – some believe it would be deal vs no Brexit, some deal vs no deal, some a vote offering all three options.

If pinned down to ask if they support any specific version of a second referendum, voters have generally been less likely to say yes, when compared to the generic question.

How the support breaks down

A new poll for the People’s Vote group – which campaigns for a second referendum – by YouGov, published in the Observer, suggests members of the three largest trade unions (who are also Labour’s biggest backers) overwhelmingly back a second vote.

The poll found trade union members generally backed a second vote by a 2-to-1 ratio, and supported remaining in the EU by a similar margin.

This largely supports the general polling figures from the different political parties. Liberal Democrat members in July backed a second referendum by 67 per cent against 20 per cent, while Labour – which is often referred to as divided on Brexit – also has strong support for a second referendum among its voters, at 58 per cent versus 24 per cent.

By contrast, Conservative voters opposed a second referendum, with only 21 per cent saying they wanted a vote, versus 67 per cent against.

This helps to explain the public position of the party frontbenches: Theresa May has ruled out supporting a referendum, a popular position among her MPs and voters – while Jeremy Corbyn, who had previously ruled out a second vote, has recently avoided commenting either way on the issue, prompting rumours of a potential change in policy.

The final line

Remain supporters are right to say that there has been a shift in public opinion both in favour of Remain and in favour of holding a second vote, but opponents are also correct to say public opinion is still sharply divided on this, and the shift has not led to an overwhelming majority either way.

The case still remains to be made – in whichever direction – but the clock is ticking: at the time of writing there are just over 200 calendar days left before the UK exits the European Union.