Demonstrators take part in a march calling for a People's Vote on the final Brexit deal in London on October 20, 2018 | Niklas Halle'n/AFP via Getty Images UK poll predicts 8-point victory for Remain in second Brexit vote Two-thirds of voters say Britain should continue to have a close relationship with the EU after Brexit.

U.K. voters would vote to remain in the EU by a majority of 54 percent if a referendum were held today, according to a poll of 20,000 people across every constituency in the country.

The unusually large poll, carried out by Survation for Channel 4, indicates a swing of 6 percentage points from Leave to Remain since the 2016 referendum and an 8-point margin in a second vote. The data also suggests that 105 local authorities that voted Leave in the original referendum would switch to Remain if a national vote on EU membership were held today.

Moreover, the poll found that if the U.K. and EU agree an exit deal, 55 percent of the voters said they would support at least one version of a second referendum, while 15 percent opposed all of the potential referendum options put to them.

U.K. Prime Minister Theresa May has repeatedly rejected the idea of holding a second Brexit vote, but the results — combined with a Hanbury Strategy poll conducted for POLITICO and published at the weekend which showed 53 percent support for Remain — are likely to spark further calls from Brexit campaigners for a referendum on the terms of Britain's eventual EU deal.

The large size of the new poll means that it can provide useful estimates about changes of opinion within the 380 individual local authorities sampled. According to the data, in every one of those but two, there is a swing toward Remain — the exceptions being the City of London and Richmondshire in Yorkshire, which in 2016 had Leave vote shares of 24.7 percent and 56.8 percent respectively. In both cases, the swing to Leave estimated by the poll is lower than 2 percentage points.

By contrast, two local authorities have estimated swings to Remain of more than a whopping 14 percentage points, according to the polling data. Newham in East London voted to Remain in 2016 (with a Leave vote share of 47.2 percent) while Leave won 62.4 percent of the votes in Barking and Dagenham in 2016. The new poll suggests the latter borough would vote to Remain if a referendum were conducted today.

Thirty-three other local authorities have experienced a swing of more than 10 points to Remain since the referendum, according to the data. And support for leaving the EU fell most dramatically in the local authorities with the highest leave vote shares in 2016.

The Survation poll also showed that 67 percent of voters said that the U.K. should continue to have a close relationship with the EU after Brexit. This is almost three times as many (23 percent) voters who believe the U.K. and EU should not have a close relationship.

Respondents also displayed some ambivalence about the potential for Brexit to prompt the breakup of the United Kingdom. Forty-four percent said they are very or quite concerned about the possibility of Northern Ireland leaving the U.K. as a result of Brexit. But 42 percent said they are not very or not at all concerned.

The equivalent figures for Scotland are 46 percent and 46 percent respectively.

The Survation poll, which was conducted between October 20 and November 2, deploys a widely used statistical technique called multi-level regression and post-stratification to predict results in individual local authorities.