SCOTTISH voters are “deciding it’s time for this country to choose its own future,” John Swinney claimed yesterday, after a new poll suggested the Union was on a knife-edge.

An Ipsos MORI survey for STV found 49 per cent of Scots now back independence while 51 per cent want to stay in the UK, but among those likely to vote it is an even 50/50.

The two-point rise in support for independence echoes a BMG poll for the Herald last month which found support at 49 per cent, up three points.

However Ipsos MORI also found backing for independence was softer than support for the Union, with only 28 per cent wholly committed to a Yes vote, against 38 per cent for a No.

The poll featured in lively exchanges at First Minister’s Questions, where Mr Swinney was standing in for Nicola Sturgeon, who was attending an armed forces event in London.

It emerged overnight that Ms Sturgeon had called the autumn of 2018 a “common sense time” for a second referendum if Theresa May rejected a bespoke Scottish deal on Brexit.

Ms Sturgeon’s spokesman later extended this to between autumn 2018 and spring 2019.

Scottish Tory leader Ruth Davidson claimed Ms Sturgeon was “gunning” for a referendum, despite a majority opposed to “the division and uncertainty” it would bring.

She said: “Most Scots think that it’s irresponsible to talk of a second referendum which is only going to damage the Scottish economy yet further. That is common sense.”

Referring to the STV poll, Mr Swinney, who is deputy First Minister as well as Education Secretary, said: “We should not be at all surprised by those numbers, as that is the people of Scotland being exposed to the hard-right politics of the Tory party, seeing the mess that it is getting us into about Europe and deciding that it is time for this country to choose its own future.”

Ms Davidson also raised an admission this week by Andrew Wilson, the former MSP leading the SNP’s Growth Commission, that it was wrong to claim in 2014 oil would be a “bonus” for an independent Scotland, when in fact it was “a basis” for the economy.

The SNP claimed North Sea Revenue would be between £6.8 and £7.9bn in Scotland’s first year outside the UK, but the oil price collapse means oil revenue is now effectively zero.

Ms Davidson said: “The economic prospectus on which the SNP based its entire case for independence was bogus.”

Mr Swinney said oil had been a “huge bonus” to the UK for 40 years, delivering £300bn to the Exchequer.

He also pointed out that in 2014 then Prime Minister David Cameron had claimed in Aberdeen that a No vote in the referendum meant a “£200bn oil boom bonus” for Scotland in the Union.

Ms Davidson said: “Oil receipts have absolutely collapsed. Without those oil receipts, can the Deputy First Minister point to any independent analysis that shows that Scotland's economy would fare better right now if we were outside the United Kingdom?"

Mr Swinney said people wanted to hear about more support for the North Sea, and criticised the UK Government for re-announcing a delayed “talking shop” in the Budget.

Scottish Labour leader Kezia Dugdale claimed the SNP gave Scots "false hope ... based on a false prospectus" in the 2014 referendum and the case for independence now "lies in tatters".

The SNP’s estimate of oil cash in the first two years of independence was £20bn out, she said.

She told MSPs: “Before the independence referendum, John Swinney said, 'The early years of an independent Scotland are timed to coincide with a massive North Sea oil boom'.

“Yesterday, the Office of Budget Responsibility confirmed that North Sea oil and gas actually cost the Treasury money last year. So can the Deputy First Minister tell us, why didn't the SNP tell the people of Scotland the truth about oil?"

Mr Swinney did not mention oil, but was loudly cheered by SNP MSPs for saying the common theme of the questions showed Labour and the Tories were back on the same side as in 2014.

He said: "Isn't it revealing that at the first available opportunity they've come back together again? I would have thought after the calamity that Kezia Dugdale led the Labour Party into in the 2016 election she might have learnt to have nothing to do with that lot over there."

Green MSP Patrick Harvie called for “major changes” to the government’s Draft Climate Change Plan, which he said was “half-baked”, its flaws compounded by contradictory statements from ministers.

Referring to recent committee scrutiny of it, he said: “It's very clear that there is serious concern and that changes to this draft plan will need to be equally serious".

Mr Swinney said the issues raised demonstrated “the rigorous scrutiny that is exercised on the Government by parliamentary committees".