LONDON (Reuters) - Britons would choose to stay in the European Union if given the option, according to an opinion poll on Wednesday that showed a six-point swing away from Brexit and the highest support for EU membership in such a survey since the 2016 referendum.

The author of the poll urged caution over the finding, however, saying the interview panel was skewed towards remain, and that some of the shift was among those who did not take part in the original Brexit referendum.

In the June 23, 2016 referendum, 17.4 million voters, or 51.9 percent of the votes cast, backed leaving the EU while 16.1 million voters, or 48.1 percent of votes cast, favoured staying. Many opinion polls were wrong about the result.

The new polling showed 59 percent of voters would now vote to remain in the bloc, versus 41 percent who would opt to leave. The findings were published in an academic-led report on Wednesday by research bodies NatCen and The UK in a Changing Europe.

That is the highest recorded support for ‘remain’ in a series of five such surveys since the 2016 referendum and a large reversal of the actual 52-48 percent vote to leave.

Polling expert John Curtice, the author of the report, cautioned that those interviewed reported they had voted 53 percent in favour of remain in the referendum -- a 5 percentage point higher proportion than the actual vote.

“Nevertheless, this still means that there has apparently been a six-point swing from Leave to Remain, larger than that registered by any of our previous rounds of interviewing, and a figure that would seemingly point to a 54 percent (Remain) vote in any second referendum held now,” Curtice said in the report.

NO DRAMATIC SHIFT

Speaking at an event to launch the report, he said the findings were broadly in line with those of other pollsters, whom he said showed an average of 52.5 percent support for remain.

“Don’t get excited as to think this is some poll that shows a dramatic shift to remain,” Curtice said. “The apparent thin lead that remain have is at least in part built on the potential sand of the responses of those who did not vote two years ago.”

Britain is due to leave the EU on March 29, 2019 but has yet to secure an exit agreement to define future relations with Brussels and manage the economic impact of ending over four decades of integration with the world’s largest trading bloc.

The government has ruled out holding a second referendum, and the opposition Labour Party is not advocating one either.

The survey interviewed 2,048 subjects between June 7 and July 8. That means the survey does not fully reflect any change in opinion brought about by the publication of Prime Minister Theresa May’s negotiating strategy, published in early July.

That negotiating strategy has split May’s Conservative party at every level and drawn heavy criticism from both Brexit supporters and those who want to retain close ties to the EU.

Nevertheless, the poll shows voters thought the negotiations were going badly even before the publication of May’s so-called Chequers plan. Curtice added that subsequent polling data, not included in the report, had shown the plan had little support from the public and was unlikely to have reversed voters’ pessimism.

He said the results of the polling showed that the most influential factor over whether voters will support the conclusion of the negotiations is their perception of its economic effect rather than the details of any deal.