Support for reversing Brexit has risen – and opposition has fallen – since Andy Burnham opened the door to Britain rejoining the European Union , according to a major new poll.

The Ipsos Mori survey found that 56 per cent of respondents now say they would vote in favour of becoming part of the EU again , up four percentage points on a similar poll in May.

At the same time, the number who back staying out has fallen three points to 30 per cent.

When the findings were filtered by those likely to vote in a future referendum, the result was 63-34, with 3 per cent saying they did not know.

Andy Burnham has said he wants to see the UK rejoin the EU (AFP/Getty)

The poll also revealed that 73 per cent of those aged under 35 want to rejoin the bloc, alongside 77 per cent of those who voted Labour at the last general election, 31 per cent of Tories and even 16 per cent of Reform voters.

Most of the public think joining the EU will improve the economy and national security, 54 and 53 per cent respectively,…