THE grassroots Yes movement is set to take the lead on independence this summer, after the SNP postponed its own initiative in light of the Brexit vote.

Party officials had insisted the programme would be rolled out “within weeks”.

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But a meeting of the SNP’s ruling National Executive Committee in Glasgow yesterday heard there was still no definite start date and limited detail on what it would involve.

Sources said Brexit had forced a full-scale rethink of the party’s message to voters.

However, grassroots campaigners said Brexit had also produced a surge in local activism, meaning there will still be a summer push on independence from rank and file Yes supporters.

Nicola Sturgeon announced the plan for a summer initiative at the SNP’s spring conference in March.

Describing the need to convince No voters, she said: “This summer the SNP will embark on a new initiative to build support for independence. It will not be an attempt to browbeat anyone.

“We will hear your concerns and address your questions - and in the process, we will be prepared to challenge some of our own answers.”

After the UK voted to leave the EU, the SNP leader said a second independence was “highly likely” within the two-year withdrawal process, raising expectations about the initiative.

Read more: SNP accuses Westminster of 12 betrayals of Scotland in last 12 months

But Brexit has also complicated matters for the SNP, who originally saw the summer initiative as part of a slow-burn campaign over a five-year parliament.

The current situation is far more dynamic, and an instinctively cautious Sturgeon is reluctant to rush into a situation she cannot predict or control.

Adding to her difficulties, the initiative was to be run by SNP deputy Stewart Hosie, but he quit in May over an affair and his replacement will not be elected until mid-October.

Senior SNP sources said the initiative was expected to involve canvassing, data collection, and political discussion within the party, but would take time to finalise.

One party insider said: “We’re now looking at late summer or autumn. Brexit has moved everything. When Nicola announced the initiative, nobody thought we were going to revisit the independence question before the early 2020s. It was a strategy to keep people involved.

“June 23 changed all that. We might be into Indyref2 by next year. In which case the initiative takes on a whole different meaning.”

Another said: “It won’t be coming out in the next couple of weeks. But it’s better to wait and get it right. The timetable has slipped but there’s lots of other stuff going on.”

In the absence of an independence drive led by SNP HQ, grassroots campaigners, many of whom are also SNP members, are now set to fill the vacuum.

Jason Baird, founder of the National Yes Registry, an online hub for independence groups, said Brexit had re-energised the Yes movement.

He said: “People thought the next referendum was five or six years away, now it’s two years. It’s concentrated everyone’s mind."

Read more: Unionists 'must present options for Scotland's EU future'​

He said the grassroots movement was complementary to the party political system, and would set its own agenda: “The leadership will come from the ground up not the top down.

“Yes headquarters is like the Festival and the grassroots is like the Fringe. It’s the Fringe that everyone really experiences the Festival through. The next referendum will be called by the political parties, but we’ll win it.”

He went on: “To get independence, we need a strong party political base to get us the referendum and show Scotland is capable of running itself. That pillar is already there.

“But we’re not independent, so there must be something else required. That thing is a strong second pillar, the Yes movement, the grassroots on the ground. Our aim is to build that pillar as tall and strong as the party political one.”

Kathleen Caskie, national coordinator of Women for Independence, said Brexit had produced a “second surge” for independence and groups would not wait for a lead from the parties.

She said: “People are champing at the bit. Groups that haven’t met for months have met again because of Brexit. There’s been a huge amount of activism at the grassroots.

“We’re happy to provide our own leadership. We want to talk to women about independence. We don’t need anyone else to tell us how to do that.”

Business for Scotland CEO Gordon MacIntyre-Kemp added: “The Brexit decision, taken against Scotland's wishes, has turned the independence referendum on its head; not only has a foundation stone of the No campaign been forcibly removed, but all the economic risk now lies with remaining a member of the self-destructing and isolated UK.”

Labour MSP Jackie Baillie said: “It is probably for the best that the SNP have decided to postpone the campaign. With so much uncertainty for people and businesses following Brexit, now is not the time to push to remove Scotland from the UK single market."

LibDem MSP Mike Rumbles added: “The SNP need to get on with the day job. Another independence push would only divide the nation further and lead to important issues like education and health continuing to fall behind in the queue.”

An SNP spokesman said: “The SNP's summer independence drive will be launching in the coming weeks - and will seek to build independence support right across the country.

“And in the aftermath of the UK's vote for Brexit, we know that more and more people are opening up to the opportunities of independence.”

Former SNP leader Gordon Wilson, who last week called for the return of Yes Scotland in readiness for the next referendum, yesterday urged caution again.

He warned SNP deputy leadership candidates not to "start a feeding frenzy" by whipping up demand for Indyref2 in their campaigns, saying: "Don't paint Nicola Sturgeon into a corner."