SNP members have voted for a “fast-track” plan to scrap the pound in an independent Scotland, defying the wishes of the party leadership

In what will likely be the key flashpoint in any second referendum, the party supported the preparation of a Scottish currency “as soon as practicable”.

Sturgeon’s allies had opposed this amendment at her party’s conference in Edinburgh yesterday, but the proposal was pushed through after a tight vote.

Sturgeon last week backed another independence referendum within two years, a policy ruled out by the Tory Government.

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At the SNP spring conference in Edinburgh yesterday, the Nationalists debated reforms to a post-independence economic policy that many in the Yes movement believe is out of date.

The 2014 referendum was dominated by the SNP Government’s plan for a post-independence currency union with the rest of the UK (rUK).

It would have resulted in Scotland sharing the pound and the infrastructure of the Bank of England with the rUK, but Labour, the LibDems and the Tories ruled out the plan.

Senior Yes campaigners believed the currency issue was a turn-off for voters and the main reason for their defeat.

Nicola Sturgeon, who succeeded Alex Salmond as SNP leader and First Minister, then set up the Growth Commission to rethink her party’s economic prospectus.

The Commission, under the chairmanship of former SNP MSP Andrew Wilson, recommended that an independent Scotland should keep the pound in an extended transition period.

However, left-wingers in the Yes movement believed the Commission’s stance, which they dubbed "sterlingisation", amounted to the SNP ceding control of monetary policy to the rUk.

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In Edinburgh yesterday, SNP depute leader Keith Brown and Scottish Government Finance Secretary Derek Mackay tabled a resolution which tried to address the concerns of critics by committing an SNP Government to establishing an independent currency.

The resolution did not provide a timescale, but instead noted that the process would be guided by an independent Scotland meeting six economic tests set by the Commission.

It added that sterling would be used until a new currency could be “safely and securely established in the interests of the whole economy”.

The leadership headed off a rival plan to set up a new currency within the first term of an independent Parliament, but Sturgeon suffered a reverse over another amendment which appeared to bring more urgency to ditching the pound:

“Conference considers that an SNP Government should take the steps necessary to enable the Scottish Parliament to authorise the preparation of a Scottish currency as soon as practicable after a vote for independence with the aim that the currency be ready for introduction as soon as practicable after Independence Day.”

Even though this amendment passed, the six tests laid down in the original motion remain in place.

George Kerevan, a former SNP MP, was one of the most senior Nationalists to speak in favour of a new currency being set up in the first term of an independent Scotland.

He described the main resolution as “vague” and said of the prospect of selling a policy of a new currency to voters without a timescale: “They’ll not be convinced.”

He also told delegates: “You will have to tell them when.”

Kerevan added that there is a “major time bomb” in the sterlingisation plan, arguing that there was “no way” of creating reserves to bail out banks that were in trouble.

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After the vote, Kerevan told The Herald on Sunday: “I am pleased the membership has forced the leadership to accept for the first time that we will introduce a new currency as soon as practicable after independence. In the meantime, I think sterlingisation will start to unravel as a policy as soon as it is put under public scrutiny.”

Pamela Nash, chief executive of the pro-UK Scotland in Union campaign group, said: “The SNP has voted to fast-track its plan to scrap the pound and put salaries, mortgages and pensions at risk.

“In a huge challenge to Nicola Sturgeon’s authority, members have snubbed her proposal and voted to complete this reckless act even sooner than she wanted.”

Jackson Carlaw, interim leader of the Scottish Tories, said: “This is a profoundly embarrassing snub for the SNP leadership. And it shows that Nicola Sturgeon is now at the beck and call of an extreme economic agenda within the SNP which would rip the pound from our pockets as soon as possible.

“It only underlines the growing need to stand up against Nicola Sturgeon and say no to a second referendum so we can focus on what matters, not the SNP’s deeply dangerous plans to dump the pound.”

Two polls published last week showed that the public are opposed to the pound being scrapped in favour of a new currency.

A Survation poll, commissioned by Scotland in Union, found that 71% of respondents wanted to continue with the pound. Around 12% backed a separate currency.

Fewer than one in 10 (7%) of the 1,012 adults polled said they wanted to use the euro instead of the pound.

A YouGov poll published by a daily newspaper yesterday also found little support for the plan to gradually introduce a new currency after independence.

The survey found that 14% of those polled backed the proposal, while 17% were in favour of the euro. Only 5% of voters expressed a preference for a new currency straight after independence.

However, other poll data by the same company was more encouraging for supporters of independence with 49% of respondents backing independence, up from 45% in YouGov’s last poll for the same newspaper in June.

Meanwhile, Sturgeon will use her keynote speech tomorrow to attack the Conservatives for opposing indyref2.

She is expected to say: “The UK Government says it will block Scotland’s right to choose.

“A right to choose mandated in not just one but two Scottish elections. And endorsed by the Scottish Parliament.”

She will also say: “On Thursday, they tried to justify their position by saying there was no upsurge in support for independence. Two days later the latest opinion poll was already proving them wrong. It shows support for independence already up.”

Sturgeon will also announce plans that could see greater regulation of short-term let firms such as Airbnb: “We are asking for views on a new system of regulation to make short term lets subject to the same controls as any other accommodation.

“We want to give councils the power to control the number of lets and ensure they make a contribution to the services they use.”