IN-DEPTH research reveals what the UK thinks about Brexit, five years after the referendum — and it's not good for Boris Johnson.

At this time in 2016, voters were preparing to go to the polls for an in-out ballot that would set the course of British politics and cement differences between the nations.

While England and Wales voted to Leave, Scotland and Northern Ireland voted to Remain.

Five years on, Brexit "still divides Britain", according to research from Scottish polling expert Sir John Curtice.

Published today, a new report from whatukthinks.org and the National Centre for Social Research (NatCen) says EU withdrawal has been "far from an unalloyed success" in the eyes of the public.

Four in five people would still cast their ballot the same way they did on the day, according to the paper — but just 21% believe the UK has left the EU with a good deal.

READ MORE: Five years of Brexit: The Scottish voters who are still be-Leavers

In contrast, 36% say we've exited with a bad deal.

However, 75% of Leave voters still expect Brexit to bring benefits to the UK — by either boosting the economy or reducing immigration.

And the research suggests that if a second referendum had been held at any time in the last five years, a "narrow lead for Remain" would have been the most likely outcome.

That's because adults who did not take part in the referendum were found to be at least twice as likely to say they'd now vote Remain than back Leave.

The findings are based on a series of 12 surveys carried out with 2000 people September 2016 and January this year.

And analysis shows a UK-wide referendum on rejoining the EU would likely see 52% vote to stay out.

READ MORE: 'Highlands & Islands need priority in £5bn Brexit funding'

That's despite "limited enthusiasm" for the Brexit deal secured by Johnson's team, particularly amongst Remainers, 53% of whom said it was a bad outcome.

Only 22% of Leavers had a negative view of the deal, but the results also reveal just 35% of this group rated the exit terms as "good" — which means only a third of those who wanted EU withdrawal are happy with the outcome of the negotiations between the Westminster government and European leaders.

Curtice, senior fellow at the National Centre for Social Research and professor of politics at Strathclyde University, commented: "Five years on, it is difficult to argue that the Brexit referendum has been an unalloyed success.

"Approval of the deal reached with the EU is limited. Although few Leave voters regret their decision, equally few Remain voters have been persuaded that Brexit is a good idea after all.

"Britain is still more or less evenly divided on the issue, just as it was five years ago."