NICOLA Sturgeon has yet to “flesh out” her plan for using the next general election as a ‘de facto’ referendum on independence, one of her MPs has conceded.

The Scottish Government wants to hold a referendum in October next year if the Supreme Court decides next week that Holyrood has the powers to do so.

If no legal route to Holyrood holding a re-run of the 2014 poll emerges, the First Minister said she would use the next UK general election as a ‘de facto referendum’ on independence – using a popular vote in favour of independence as justification for Scotland leaving the UK.

The First Minister was pressed on BBC's Sunday with Laura Kuenssberg over her plan B to treat the next UK general election as a de facto referendum, despite previously warning the strategy was a “unionist trap”.

Ms Sturgeon insisted that the plan “is not my preference”, but stressed “we have to have an alternative” if “democracy is blocked” by the UK Government.

She added: “The choice is then simple – we put the case to people in a referendum or we give up on Scottish democracy.

“It should be a last resort. I don’t want to be in that position – I want to have a lawful referendum."

But SNP MP Joanna Cherry, who has previously clashed with the First Minister, acknowledged the plans for how that would work in reality has not being drawn up.

Also speaking on the same programme, Ms Cherry said: “I agree with everything the First Minister has said.”

She added: “I’m in agreement with the First Minister that she doesn’t need to flesh out her strategy on how she would use a general election as a plebiscite until we see the outcome of the Supreme Court case.

“If we cannot do that, we need some sort of democratic event to demonstrate the balance of opinion has changed since 2014 so I’m with the First Minister on the strategy.”

But she hinted at the frustration by some in the party, including Ms Cherry herself, that it has taken some time for an alternative plan to be set out.

She said: “It’s some time now since I first advocated that we should test the legal case.”

Ms Cherry also claimed that if the Scottish Government loses the Supreme Court case next week, Tory ministers should still open up discussions with Holyrood over independence.

She said: “Even if we lose the Supreme Court case, that wouldn’t stop the British Government from coming to the negotiating table and that’s what they should do.

“I would caution people against assuming that we are going to lose the case.”