LISTENING to Willie Rennie recall the Better Together campaign is like eavesdropping on a therapy session as he wrestles with a half-buried trauma. The misery simply pours out of him.

The No side was “shambolic in its development”, groans the Scottish LibDem leader, its output “dark”, its operations “secretive”, people’s confidence was “crushed” by the lack of information.

Yes, they won in the end, but how they won “didn’t make us feel very good about it”.

And as for the aftermath, David Cameron was “despicable,” he spits. “I thought he did more damage in the general election campaign to the Union than the SNP had done for years.”

So not a barrel of laughs, then. Indeed, while the Yes side now boasts thousands of upbeat losers, Rennie seems the embodiment of that other Scottish tribe, the joyless Unionist victor.

Perhaps he should have anticipated a rough ride when Better Together’s launch went awry.

Although he grinned dutifully for the cameras that day, Rennie reveals he couldn’t properly focus because the late Charles Kennedy had failed to show up.

“We suspect it was another one of his episodes. That’s what my mind was flooded with.”

After that, it was mostly downhill all the way for the Labour-Libdem-Tory alliance.

Because the only thing the parties shared was a dislike of independence, the campaign became overwhelmingly negative by default, Rennie explains.

“It was a clash of three different political parties. We all had very different visions for the union, so inevitably the common element was what we were against, which was independence.

“So to get a consensus, you were focusing on the negative. You couldn’t do a positive vision.”

Then there were the bad habits of those at the top.

“Labour had a dark campaigning style. It was very secretive. Everything would be last minute. You would never be told much about what was going on until it happened. We all suffered. The Tories and ourselves suffered more, but some in Labour were out of the loop as well.”

You mean an inner circle ran everything? “Yes. It was Blair [McDougall, campaign director] and Rob [Shorthouse, communications director]. People like that were making decisions and had this addiction to secrecy. It was a fear of the other side finding out what we were planning.

“It was quite shambolic in its development. Internal comms was poor. You just weren’t told about plans. Things were kept back. The board were frustrated at times as well.”

The Tories were also trouble, and in the early days had to be talked out of trying to dictate the referendum process from Westminster, instead of devolving control to Holyrood.

“We had to try and control the Conservatives as much as we could. They had a very gung-ho approach to things, very aggressive, very direct. We in government had to pull them back.”

What about George Osborne coming to Edinburgh and saying 'Thou shalt not have the pound'?

“His style of delivery, yes, that was poor,” he says. Using George Galloway to defend the union in a debate for schoolchildren at Glasgow’s Hydro was another tin-eared error, he adds.

“He was a monster maverick. You want to give people confidence in the UK, not mavericks.”

The “top-down, politically led” nature of Better Together meant it missed a huge opportunity to grow a community-led campaign of the kind Yes Scotland fostered, says Rennie.

“We were talking a different language. We were making a case - they had a cause. That changed the whole nature of it. And when they [Yes] started occupying the squares and towns and it had that East European feel, it made us gulp. You could feel it moving.”

He felt things turn around when big businesses such as RBS issued “very stark” warnings about the financial consequences of independence.

Better Together benefited from solid logistics as well, targeting its messages at key voters.

“The emotional side was poor, but the mechanical bit was there,” he says with faint praise.

Jim Murphy’s road trips also lifted Unionist morale, he says, as did the Yes camp’s errors.

“They certainly fell down on the currency. The lack of economic plans was pretty firmly a mistake. People were worried on the door about currency. They also fell down on the slightly overbearing, aggressive nature of the campaign. That created an atmosphere.”

He thinks another referendum “could well happen”, but also believes people aren’t in any hurry to return to the “conflict between neighbours, friends and relatives” of last year.

“My feeling is [the SNP] will wait till people are begging for it”, he says, before another referendum.

If there is another what what you do differently?

“Make sure it was led by non-political, non-partisan people. A common purpose .. an organic campaign. More colourful, more joyful, more positive about the benefits of the UK.”

It’s hard to imagine him reaching out to David Cameron for help, however.

The way the Prime Minister used the No result to advance English Votes for English Laws, then exploited English-Scottish division in the general election, was appalling, Rennie says.

Like Gordon Brown, he thinks Cameron’s stoking of English nationalism imperils the Union.

“I thought Cameron was despicable. The way that, within a matter of months of having helped us save the United Kingdom, he was prepared to put his party before his country.

“The Alex Salmond pickpocket [election ad] was despicable, just despicable. For somebody who calls himself first and foremost a Unionist, you don’t behave like that.”

If there’s another referendum would you throw yourself into it the fray again or pass? Surprisingly perhaps, given the trail of tears he tramped in 2012-14, he’d jump at the chance.

“I’d definitely do it. But we need to get better next time. More open, more trusting, more positive about the country, and present a bright vision for where we want to be. To be fair, that’s what the SNP managed to sell quite effectively. It was all hogwash. But they sold it quite well, and that’s to their credit. I just wish we could do a bit of that ourselves.”