Leaders of Scotland, Wales and Northern Ireland, as well as the President of Sinn Fein (Image: Getty)

Nationalist leaders in Scotland, Wales and Northern Ireland have agreed to work together to break up the United Kingdom. Scottish First Minister John Swinney declared that Andy Burnham will be the last Prime Minister to govern the UK in its current form, as he signed a memorandum of understanding with his counterparts.

Northern Ireland’s First Minister, Michelle O’Neill, revealed she took encouragement from US President Donald Trump, after he declared over the weekend that a united Ireland would be a “fantastic thing”. And Welsh First Minister Rhun ap Iorwerth said there was a “determination that it was for our people to decide” their futures. All three nations are currently led by politicians committed to leaving the UK, after Welsh nationalists Plaid Cymru ended 27 years of Labour rule in May’s elections.

The SNP, which is committed to Scottish independence, has run the Scottish government since 2007 while Sinn Fein politician Mrs O’Neill became First Minister of Northern Ireland in February. Her party calls for the province to leave the UK and unite with the Republic of Ireland.

In a joint statement demanding referendums to determine the future of each nation, the leaders declared: “Westminster’s time is coming to an end”.

Launching their campaign in Cardiff, they called on the UK Government to “prepare for, plan and facilitate constitutional change in each jurisdiction”.

Mr Swinney insisted Scots would vote to leave the union if a poll was held today, despite rejecting independence by 55%-45% in a 2014 referendum.

And he claimed that Mr Burnham’s commitment to devolution in England, which involves giving more powers to regional mayors, “leads you to the logic of recognising the right of the people of Scotland, in my case, to decide their own future”.

The Scottish leader said: “I think he will be the last prime minister of the United Kingdom, because the people of Scotland, if given the choice of independence in a referendum will take that choice,”

Mrs O’Neill welcomed Donald Trump’s comments in support of Irish unity, after the US President said he “would love to see” Ireland unified.

Accompanied by Sinn Féin president Mary Lou McDonald, the leader of the opposition in the Irish Dáil, Mrs O’Neill said: “The comments from the president of the United States very much reflect the fact that the unity debate is very much alive, and people are engaged in it, not just at home, but obviously now internationally as well.”

Downing Street insisted the Prime Minister believes strongly in the United Kingdom and is focused on easing the cost-of-living crisis for households across the country rather than on “constitutional debates”.

Mr Burnham’s spokesman said: “The Prime Minister is committed to delivering change across all four nations of the United Kingdom and believes strongly in the Union.

“The United Kingdom is at its best when people come together around our shared values and problem-solving, rather than division, and the Prime Minister will continue to ease pressures on household finances, and delivering greater economic security, rather than engaging in constitutional debates or further referendums.”

Conservative leader Kemi Badenoch said: “Building a country requires a lot of work. It requires a lot of effort, and it isn’t something that we should take for granted.

“But if all we’re talking about is how to get out, we’re not actually bringing people together.”