Barely a third of the public in Great Britain hope Northern Ireland would vote to remain in the UK, new research showed.
A fifth said they would prefer it left and joined the Republic of Ireland following any future referendum on removing the Irish border, pollsters revealed.
One in three (34%) thought Brexit will make it more likely that Northern Ireland will join the Republic over the next decade.
More of those who voted Remain in the referendum than of those who voted Leave think Brexit will make a united Ireland more likely.
The research was published by market research organisation Ipsos MORI for King’s College London.
Roger Mortimore, professor of public opinion and political analysis at King’s College London, said: “When Scotland voted on whether to become independent in 2014, there was a clear majority among the public in the rest of the UK that hoped it would choose to stay.
“But many fewer Britons, it seems, would mind if Northern Ireland decided to leave the Union.
“Most have never been there, and most have no clear view on how it will be affected by Brexit.”
Conservatives are most likely to hope that Northern Ireland would vote to stay in the UK: 49% of those who would currently vote Conservative say they would prefer Northern Ireland to vote to stay, compared to 34% of Labour supporters and 27% of Liberal Democrats.
Those who voted for Britain to Remain in the EU in the 2016 referendum are more likely (23%) to want Northern Ireland to leave the Union and join the Republic than those who voted Leave (15%).
Three in four adults who live in Great Britain have never visited Northern Ireland, and a further 17% have visited only once or twice. Just 3% have lived or worked there, and 5% have visited many times.