Nicola Sturgeon's chances of winning a second vote on Scottish independence will depend on the progress of Brexit talks and how well her party tackles economic challenges, according to a leading historian.
Prime Minister Theresa May has criticised Scottish National Party's drum beating for a second independence referendum to break away from United Kingdom as lacking an "economic case".
The No vote secured 55 per cent at the 2014 referendum.
She said as Britain leaves the European Union the opportunity must be taken to bring Britain closer together.
"I think the SNP needs to move away from the tunnel vision of the issue independence and actually focus on the issues that that matter to people on a day to day basis", she said. "To me politics isn't a game".
Mrs May will tell party members in Glasgow: "Politics is not a game and the management of devolved public services is too important to be neglected".
Speaking on the Good Morning Scotland programme she said: "You've got a nationalist Government, hell-bent on breaking us up, they told us it was a once in a generation decision".
May also said that no decisions now taken by the Scottish parliament will be removed from it when Britain leaves the EU. Scotland voted 62% in favour of the United Kingdom remaining within the EU.
During a lengthy historical section, she sought to portray the Union as a remarkable team effort which had produced everything from penicillin (discovered by a Scottish doctor in a London hospital) to the Harry Potter books (written in Edinburgh by an English-born author).
A day later, a spokeswoman for May said that the United Kingdom government did not see any changes in public opinion that could serve as a reason for holding the second referendum on Scottish independence.
The latest clash between Mrs May and Ms Sturgeon comes as the first minister is expected to announce plans for a second independence referendum when the PM triggers Article 50 for the United Kingdom to leave the European Union later this month.
Over the cliff-edge The SNP's deputy leader Angus Robertson dismissed Ms May's remarks as hypocritical and surreal, accusing her of seeking to drag Scotland and the rest of Britain over the cliff-edge of a hard Brexit.
"The UK devolution settlements were designed in 1998 without any thought of a potential Brexit", she said.
"In those circumstances, we have a duty to stand up for Scotland, and to have a plan in place to protect our vital national interests".
Scottish First Minister Nicola Sturgeon has been demanding substantial new powers are transferred to Holyrood following Brexit.
"That's a fundamental attack on the very principle and foundation in statute of the Scottish Parliament of 1999, which said specifically that anything that wasn't reserved to Westminster should be run in Scotland".