SECRET work led by SNP executive Peter Murrell has begun to prepare for the launch of a new cross-party independence campaign.

It involves creating a war chest as part of work to help "design a new Yes Scotland 2-style body", a source confirmed.

Nicola Sturgeon's battle of wills with Theresa May about the timing of an independence referendum is likely to dominate the political agenda for months, however, the issue of how any Yes campaign will be fought has yet to be publicly aired.

The SNP leadership has decided to focus its full energies during the next few months on obtaining a Section 30 order from Westminster that would allow for a legally-binding referendum to be held.

However, the Sunday Herald spoke to leading figures in the independence movement about the work already going on behind the scenes to ensure a campaign could be launched soon after any referendum deal is reached. Since Nicola Sturgeon announced her intention to a hold a new referendum on Monday the SNP has raised almost £350,000 to help fund the Yes campaign.

Murrell, who is also Sturgeon's husband, has contacted senior pro-independence figures about preparing for the launch of a new campaign, while the party deals with Section 30 issues.

He was in touch with Scottish Independence Convention (SIC) leaders about that work the day Sturgeon announced she would seek permission from Westminster for a referendum between autumn 2018 and the spring of the following year.

Overseas political strategists and senior figures from the Alex Salmond era will also be tapped up to ensure enough campaign personnel are in place.

Polling and focus groups will also be commissioned in the months ahead to help identify weaknesses from last time around and plan a new campaign.

Setting up an instant rebuttal unit to deal with concerted attacks from the No campaign over issues such as Europe and currency will also be explored.

However, a key task will be to approach pro-independence donors from 2014, such as the UK's biggest lottery winners, Colin and Christine Weir, who will be asked to bankroll a Yes Scotland 2 push. SIC's chair Elaine C Smith will sound them out.

The Weirs, from Ayrshire, have been the independence cause’s most generous benefactors since they won the £161 million jackpot in 2011. During the first three months of 2015 they gave £500,000 each to the SNP.

They also donated a further £1 million to Yes Scotland in the run up to the 2014 referendum.

A senior source confirmed to the Sunday Herald that the Weirs will be asked to dip into their pocket once again to support independence.

The SNP is already on board with the cross party SIC, which has MPs Tommy Sheppard, Dr Philippa Whitford and MSP Ivan McKee already on its organising committee.

Salmond's former chief of staff Geoff Aberdein was last week also understood to have been in talks with SIC's chair, in a move that would mean the group had a major link to the SNP hierarchy.

Aberdein was a special adviser to the former First Minister for four years, then his chief of staff for three. He is now head of public affairs at Aberdeen Asset Management.

Yes Scotland, which had an advisory board and full-time staff, was dismantled soon after the 2014 referendum.

However, last night, a source said that while SIC would not form a Yes Scotland2 campaign it was hoped it "could give birth to it" if a Section 30 order is granted.

A series of focus groups and extensive polling will be commissioned by SIC between now and the SNP's autumn conference to help inform how a second referendum campaign could be fought.

There will also be attempts to make contact with experienced campaigners from overseas, who could potentially be brought in to take charge of strategy.

However, a source said any campaign would move away from the "heavy management structure" of Yes Scotland in 2014 when powerful roles were held by figures such as Blair Jenkins who served as its chief executive.

Last night, Elaine C Smith, confirmed that SIC was carrying out background work for a second pro-independence campaign.

She said: "We have a detailed work plan which is all about preparing the ground and doing background work to get us ready to fight a campaign.

"We’re talking to everyone we can and we hope that we can make a very helpful contribution to designing and getting ready for the biggest campaign of our lives.”

SNP MP Tommy Sheppard said: "It's important that all parts of the independence movement can talk together to get the best campaign possible prepared for when the time comes.

"We need to draw on the best skills we can find and they will exist in different political parties and in none.”