A MAJORITY win at the next Holyrood election would give the SNP a “democratic mandate” for a second independence referendum, the Scottish Secretary has accepted.

Contradicting Boris Johnson’s vow to block Indyref2 come what may, Alister Jack indicated an outright SNP win in 2021 would pave the way for a fresh vote on the constitution.

The SNP said it showed Tory resistance to Indyref2 was "crumbling".

Referring to the transfer of power required for a legal referendum, Mr Jack told BBC Radio Scotland: “The democratic mandate for a Section 30 order is a matter for 2021. We’ll see whether or not the Scottish National Party get a majority then.”

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Ms Sturgeon has said she wants Indyref2 in the second half of 2020, and that winning a majority of MPs in the general election would give her a mandate to hold it.

However Mr Johnson, who has given himself the title Minister for the Union, has said he will not countenance another referendum.

He told the Herald this week he would never agree to empowering Holyrood to hold the vote.

“I'm ruling it out. It's a bad idea," he said.  Asked if there were any circumstances in which he would change his mind, he replied: "No. People don't think referendums are proving to be brilliantly healing as political devices in our country."

But Mr Jack said he agreed with former Scottish Tory leader Ruth Davidson, who said in the summer that an outright SNP majority in 2021 would trigger the Indyref2 process, just as the SNP majority of 2011 led to the referendum of 2014.

Mr Jack, who is defending his Dumfries & Galloway seat on December 12,  was asked about Mr Johnson refusing to debate Nicola Sturgeon in the general election.

He said: “He’s quite right to say that he won’t debate her on the basis that she’s not a candidate to be Prime Minister.”

Asked if Mr Johnson was running scared of debating Ms Sturgeon, he said: “He’s not running scared at all. He’s made it very clear that the once in a generation decision was taken in 2014, and he’s made it very clear that  we do not support a second independence referendum. We believe that decision was taken. 

“We should take away the uncertainty, as we believe we should with Brexit, remove the uncertainty of independence, start growing the Scottish economy.”

Asked if the SNP winning most of Scotland’s 59 seats in the general election would give it a democractic mandate for a Section 30 order, the transfer of power to hold Indyref2, Mr Jack said: “No.”

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Asked why not, he said: “Because the democratic mandate for a Section 30 order is a matter for 2021. We’ll see whether or not the Scottish National Party get a majority then.

“I mean the Scottish National Party - not in collaboration with other parties, not in any alliances - but a Scottish National Party majority, which is what Ruth Davidson pointed out some months ago.”

In June, Ms Davidson, while leader of the Scottish Tories, said an outright majority was the threshold to begin negotiations on Indyref2.

She told the BBC: "If she [Ms Sturgeon] puts it in a [Holyrood] manifesto that she's going to hold another referendum and she wins a majority outright, then she can negotiate with the UK government in the same way as happened last time.

"But she doesn't get to just, in the middle of a parliament where she's lost her majority, get to stick her hand up and say I'm going to re-run this referendum again and again until I get the result I want."

Richard Arkless, the SNP challenger in Dumfries & Galloway, said:  “Whether and when to hold an independence referendum must be a matter for the people of Scotland - not out of touch Westminster politicians.

"It is totally unacceptable for Boris Johnson to say he will overrule the people of Scotland if the SNP wins this or any other election, or for Alistair Jack now to say the Tories will decide which election does or does not count as a mandate.

"Both Labour and the Tories are all over the place on this issue because their position is undemocratic, unsustainable and crumbling. 

“A vote for the SNP will send a strong message that the future of Scotland is for the people of Scotland to decide not arrogant Westminster Tories."