Patrick Harvie does not agree with those who say the problem in 2014 was that the public was not ready to say Yes. The real problem, he says, is that what the SNP ran was “a media campaign”, not a grassroots campaign.

The Scottish Green Party co-leader, who during Scotland's independence referendum campaign said, “You don’t need to like Alex Salmond to vote Yes”, remains critical of the then First Minister’s role.

“I always wondered about Salmond’s decision. He basically set up Yes Scotland, announced who was going to be on it, and then invited us along to take part, rather than building a shared campaign from the ground up. What he set up seemed more like a media campaign and I have wondered what Yes Scotland would have been like if it had been run by somebody who had grassroots campaigning experience.”

The relationship between Harvie and Salmond was never smooth. That much was clear from the fact that in June 2012, a fortnight after Patrick Harvie and Alex Salmond launched the Yes Scotland campaign at Edinburgh Cineworld, the Scottish Greens pulled out.

A statement published on the party’s website said: "If we are to formally sign up as a party we need to know on what terms. We don't want to end up simply cheerleading for the SNP.”

But the Greens came back on board, and what evolved were two campaigns, working in parallel, one in the media, and another on the ground, with the Scottish Greens straddling both, and participating in the Radical Independence Campaign.

Harvie recalls one moment in the referendum run-up when he thought that goal of independence might be within reach. “I remember," he says, "the feeling I had on the bus going into town on the night just before the count had begun. I was going to join the throng in the city centre before heading to do punditry at the BBC and for the first moment, I thought, ‘Maybe we’ve done it.’

“That was quite a heart-pumping, hair-standing-on-end moment. Of course, I was wrong. But I think I’ll remember that because I want not just me, but Scotland, to have a chance to feel that again”.

Ten years on, following a UK general election Labour landslide, it seems there's a long way to travel before hairs once more stand on end. Does he think that feeling could come again any time soon?

“This year,” he says, “has been challenging because the whole sense of change has gravitated towards getting rid of the Tory government. That’s a totally legitimate goal and one I absolutely share and I can understand why people focus on that as the route to change in the short term.

"I think increasingly over the next few years we’re going to see more examples, whether it’s winter fuel payment or two-child limit, of things that will remind people just how unimpressive a centrist Labour government can be and will remind people that there’s a case for us doing things better for ourselves.”

“I genuinely think,” he adds, “the powerful force here is public appetite, and that appetite at the moment, in the wake of a UK election, has been for change to come from elsewhere. There’s an impatience and an anger with stuff that doesn’t work, and that we are missing out on an opportunity for a more equal society. I can understand it, but I don’t think it’s likely to be satisfied by the UK Government.”

It has been said by Michael Collie, the Scottish Green Party member behind the original proposal that the Scottish Greens adopt independence as policy, that the referendum was the “the making” of the Scottish Greens “and Harvie in particular”.

Harvie, who had already been an MSP for a little over a decade at the time of the referendum, had not always been a believer in independence. “I went to Manchester University and I think even by the time I came back, I probably wouldn’t have thought very much about independence and if I had  it would have been pretty sceptical.”

However, by the time he joined the Greens, off the back of campaigning over Section 28, he was, he says, “open to the idea” and soon became convinced by the argument that “a Green vision for our society is better delivered on the scale of a country like Scotland.”

He recalls how “transformational” the referendum was for the party. “Unquestionably it gave us a platform that we hadn’t had before.”

When he joined the party, he said, there were around 400 members across the whole of Scotland and “a Glasgow Branch meeting would have been lucky to get five or six.” But by referendum day there were 1300 members and the party came out of that night with between "six and seven thousand". That figure carried on rising to a high of about 9000. “We’re sitting at about 7-7,500 thereabouts now,” he notes.

It was a stampede that mirrored that of the SNP, which rose, on a similar-shaped graph, between 2013 and 2015, from just over 20,000 to nearly 120,000. More recently it dropped to half that.

The thrill of that membership surge was a referendum highlight for Harvie. “We were having meetings of both the Glasgow and Edinburgh Greens where the number of people turning up to the branch meetings was way more than the rooms could accommodate.”

Patrick Harvie (left) campaigning for Yes Patrick Harvie (left) campaigning for Yes

But, of course, not all the party backed Yes. Famously former-leader Robin Harper declared that he was voting ‘No’ and last year resigned from the party, saying it had “lost the plot” and citing its position on independence and handling of "the situation with the trans community.”.

Harvie recalls the mix of stances within the party in 2014: “We were the only party that I’m aware of that took part in a hustings where you had a Green person on both sides of the debate. I was on the pro-independence side of and a member of the Glasgow branch who was a councillor at the time was on the ‘no’ side. That was something that was really important for us to model, that you can disagree about this and still be friends.”

But without a doubt, the Green policy on constitution must have meant votes have been lost - as well as gained - in elections since. Harvie concedes that this is sometimes the case. “When I’ve been out canvassing I’ve met a few people who say, ‘I might want to vote Green but I can’t vote for a pro-independence party.’ ”

The key job for the independence movement remains, he believes, to grow support from the ground up. “Lots of people in the independence movement have been saying this for a while now - building that support is the critical thing we need to do. There is not some magic fix, or clever wheeze that gets you to Independence without building more support.”

For the Scottish Green Party, the independence referendum was also a part of a wider political journey. Without it and the alliance for Yes forged, it seems unlikely that the Scottish Greens would have found themselves signing of the Bute House Agreement, or in Government with two Scottish Green ministers (Harvie and Lorna Slater), or fighting the UK Government over the Deposit Return Scheme, or experiencing their recent ousting by Humza Yousaf before he himself fell on his sword.

Patrick Harvie and Lorna Slater give a press conferencePatrick Harvie and Lorna Slater give a press conference (Image: PA)

“It’s that slightly glib definition of history,” says Harvie. “It’s just one damn thing after another. The Bute House Agreement was built on trust. It wouldn’t have existed if there wasn’t a good degree of trust between ourselves and in particular Nicola and the people around her. She had enough trust to pick up the phone to us to say, let’s talk about building a closer working relationship.”

“Some of that building of trust took place during the referendum campaign, during which I always had a bit more time for Nicola Sturgeon than I had for the then First Minister. Nicola had been on the advisory board of Yes Scotland and I was on it for most of that period as well. I think after that, and also observing her time as First Minister, thought she had substance.”

The Bute agreement now over, he reflects: “It’s pretty tragic that some of that trust is being deliberately ripped up.”

Would the Scottish Greens consider working with, even forming a government, with Scottish Labour? Or is support for Independence key?

“The polls,” he says, “are looking very balanced. And looking at some of them, the biggest worry is how you would get a majority for anything on any issue. On individual issues we do work with anyone and always have done. If there was a change of government in Scotland, I don’t know yet what kind of Labour party we would be electing and I don’t know what their positions are going to be on some of the issues that are important to us.

“But it wouldn’t change our position on independence. Our position would be what it is now - unless our party membership voted to change the policy and I see no prospect of that whatsoever. I certainly wouldn’t vote to change it.”

What he would like to see, he says, is “a pro-Independence majority in the next election”. “I’ll argue for that. My colleagues will all work together to get as many Greens elected as we can. If there’s a pro-Independence majority we will continue to make Scotland should have the right to choose.

"If there isn’t a pro-Independence majority then we will still have to find ways to work across party lines with the SNP and with others: those who believe in a fairer and more equal Scotland, those who believe in redistribution of wealth from those who hoard it, those who believe in a fast just transition that actually gets us back on track for the climate targets that have been missed over so many years.”