Most voters now want the UK to stay in the European Union, analysis of a series of polls has found.
Remain has had an average four-point lead during 2018, a reversal of the gap in the 2016 referendum.
It comes as separate research found an overwhelming majority of English Conservatives believe Scottish independence or the collapse of the Northern Ireland peace process are a price worth paying for Brexit.
The Brexit negotiations are entering the crucial final stages, with EU leaders preparing to meet next week in the hope of finding a solution to the outstanding exit issues.
Analysis of 149 polls found Remain is now consistently ahead of Leave.
Remain gained a two-point lead over the last six months of 2017, according to the study.
Anthony Wells, director of political research at YouGov, told the Evening Standard: “The weight of evidence means that we can be as good as certain that, at least as far as the polls are concerned, Remain is now ahead of Leave.
“Between them the four trackers have asked the question 61 times this year, and 57 of them were Remain.”
Research carried out by the universities of Edinburgh and Cardiff found 79% of English Conservatives would support Scottish independence and 75% the collapse of the peace process to ensure Brexit went ahead.
Richard Wyn Jones, Professor of Welsh Politics at Cardiff University, said: “Strident protestations of faith in the future of the Union of Great Britain and Northern Ireland from Theresa May and her leading ministers cannot hide the fact that that the Union is under huge stress as result of Brexit.
“Ironically, that threat is posed at least as much by those who would regard themselves as unionists as it is by those in Scotland, Wales and Northern Ireland who actively wish the union’s demise.”
:: Surveys for The Future Of England Study were carried out by YouGov and Lucid Talk.
Some 2,741 adults in England, 2,016 in Wales, 1,502 in Scotland and 1,089 in Northern Ireland were surveyed at different periods between May 30 and July 2.
