Nicola Sturgeon says she 'doesn't know' whether to call a second independence vote

However she predicted another vote on EU membership “may become very hard to resist”.

Ms Sturgeon also revealed she had found it impossible to achieve any rapport with Theresa May, describing the Prime Minister as being as cold and impersonal in private as in public.

Unlike David Cameron, with whom she could “have a bit of banter”, Mrs May was always the same one-dimensional figure voters turned against in the election, Ms Sturgeon said.

She said: “This is a woman who sits in meetings where it’s just the two of you and reads from a script... It was just impossible to get any human connection.”

Ms Sturgeon’s hesitancy over the timing of a new independence referendum contrasts markedly with her previous declarations that she had a “cast-iron mandate” to hold it in this parliament because of Brexit taking Scotland out of the EU against its will.

However her decision in March to call a fresh vote by mid-2019 was seen as a key factor in the SNP losing a third of its MPs and half-a-million votes in June’s snap election.

In the aftermath, the First Minister said she would reflect carefully on the result.

In June, she told MSPs that after the terms of Brexit were clearer in autumn 2018 she would set out her government’s “judgment on the best way forward at that time, including our view on the precise timescale for offering people a choice over the country’s future”.

However she said a second referendum remained “likely” before the 2021 election.

But in her interview with Herald columnist Chris Deerin, Ms Sturgeon was less certain and appeared to lay the ground for possible retreat ahead of next month’s SNP conference.

Asked if her position on timing was “roughly the same” as before the summer, she said: “The honest answer to that is I do not know. Is it different to what I said previously? Yes.

“Previously, rightly or wrongly, I was of the view we should decide now, that at this point of time, give or take, depending on exactly when it [Brexit] became clear, we should do this.

“I am now saying – ok, people are not ready to decide now that we will do that, so we have to come back to that and decide, when things are clearer, whether we want to do it and what timescale we want to do it.”

Since the election, the economic case for independence has taken a battering.

Last month the Scottish Government’s own data showed SNP ministers over-estimated the health of the economy in the first year of independence by up to £10.6bn, by relying on income from the North Sea that was wiped out by the oil price slump.

Ms Sturgeon was conspicuously more confident about a second EU referendum, a so-called ‘Exit from Brexit’, as promoted by the new UK Liberal Democrat leader Sir Vince Cable.

Asked if she might back a vote on the final withdrawal package, she decried the lack of a detailed Brexit prospectus: “I think it probably gets more and more difficult to resist it,” and .

Like many familiar leaders conscious of the need to look vigorous, Ms Sturgeon also revealed she had recently taking up jogging, but was finding it tough going.

“I will eventually get to the point where I can run for more than 100 yards at a time,” she said.

Tory MSP Adam Tomkins said: “Perhaps this admission from Nicola Sturgeon explains why the SNP has been so rattled of late.

“For the nationalists their dream is over - they know another divisive and disruptive independence referendum is not going to happen in their lifetime.”

A Scottish Labour source said: "Nicola Sturgeon's time would be better spent trying to fix Scotland's schools and hospitals rather than trying to decide when is best for her to try for another referendum."

Scottish LibDem leader Willie Rennie welcomed Ms Sturgeon’s comment on a second EU vote: “It suggests the SNP are ready to join our campaign to give people the right to reject a bad deal. It should not be left to Theresa May to decide if the Brexit deal is good enough.”