RUTH Davidson has said she regrets “not putting the boot in” to the losing side in the 2014 independence referendum.

The former Scottish Conservative leader said it was a “huge strategic error” by the Unionist side not to press home its advantage and keep undermining the Nationalist cause.

She said the UK was now working on a “new Union story” that did not rely as heavily on attacking the economic case for independence.

The SNP said the Tories were in 'panic mode' over support for Yes.

After the referendum, the SNP’s membership grew five-fold to 125,000, and in 2015 it won 56 of the 59 Scottish seats in the general election.

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It currently has 48 MPs and support for Yes is at 54 per cent in the polls, which also predict an SNP landslide at Holyrood next year.

Despite making himself minister for the Union, Boris Johnson’s personal approval ratings are dire north of the border, especially compared to those for Nicola Sturgeon. 

Ms Davidson, who stands down as the MSP for Edinburgh Central next year after a decade in the Scottish Parliament, is now understood to be working with Downing Street on saving the Union.

Speaking to the Sunday Times, Ms Davidson said the Unionist camp should have been far more aggressive after the 2014 referendum, rather than letting the Yes side rebound.

She said: “Mistakes have been made, and one of those was not sticking the boot in after the 2014 referendum.

“We wanted the country to come back together and we were, if you like, interested in showing ourselves to be bigger people than them.

“That was, morally, the right thing to do, but tactically it was a mistake. A huge strategic error in fact.”

She went on: “I’m not as depressed as a number of unionists seem to be right now. 

“That’s not because I’m complacent. I can read a poll as well as anyone and see long-term trends in data.

“However, the fundamental strengths of working across the UK remain. 

“So too do the fundamental weaknesses of pro-Indy positions on key economic elements such as currency, central bank.

“That’s not enough, and we know that, and work is going on to develop a new Union story.

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“But I do disagree with those who think the SNP trajectory is inevitably ever upwards.”

On Twitter, SNP Constitution Secretary Mike Russell contrasted Ms Davidson's comments with the speech she gave to the Scottish Parliament four days after the result was declared.

He quoted her saying: "It is time for the country to move forward with common cause."

However Ms Davidson said in the same speech that that would require the leadership of the SNP to accept the result.

"Since Friday, we have had three senior nationalists, including the First Minister, saying that there are other ways to unilaterally declare independence," she said.

"We need those at the top to respect and accept the result because, without such acceptance, we cannot move on - and move on we must."

In the wake of the 2014 result, Ms Davidson turned on her fellow Unionist campaigners in order to boost her own prospects at the 2016 Holyrood election.

She said Labour and the Liberal Democrats could not be trusted with the future of the UK, a message that led to the Scottish Tories getting their best ever Holyrood result.

Ms Davidson, a prominent Remain campaigner, stood down as leader of the Scottish Tories in August last year, a month after Mr Johnson became PM.

She cited the demands of a young family but also the 'conflict' she felt over Brexit.

SNP deputy leader Keith Brown said: “The problem for Ruth Davidson is that Westminster very much has been ‘sticking the boot in’ since the 2014 referendum result.

"Before that vote, we were told that the UK was a partnership of equals – but since that vote, the Tories have dragged us out of the EU against our will, are trampling all over the powers of the Scottish Parliament and are putting our NHS and key Scottish industries under threat in a desperate bid to secure trade deals.

“Majority support for an independence referendum is now the consistent position in poll after poll and it’s no wonder the Tories are in panic mode.

"An ever-increasing number of people in Scotland now agree that the only way to properly protect Scotland's interests is by becoming an independent country."