ANDY Burnham is in the bunker. His campaign to become Labour leader has brought him to Edinburgh South, the party’s last Westminster seat in Scotland. He tells 100 souls at Morningside’s Cluny Church that he is their route to salvation, the “unifier” who can bring the party together after its bruising contest and reconnect with the electorate.

He knows why Labour has fallen from grace, he says, and he wants people in Scotland and the rest of the country to understand that he understands their disillusion.

With his slick pitch, doe eyes and Lego hair, Burnham is a bad fit for these anti-politics times. Too neat somehow, too plastic. If Ken from Ken and Barbie was a politician, he’d look like this. Yet the bland appearance is deceptive. If Jeremy Corbyn hadn’t edged into the race, Burnham would now be the most left-wing and radical of the three contenders...relatively speaking.

His manifesto promises “the most radical and far-reaching Labour vision for the country since the 1945 post-war Attlee Government” in order to “civilise” the 21st century.

Policies include re-nationalising rail, a union-devised industrial strategy, a fairer minimum wage, more social housing, house of lords reform, making social care free within the NHS. Others, such as swapping tuition fees for a graduate tax and renewing Trident, are more timid, but overall it’s a more surprising package than the wrapping suggests.

So how did it come to this? How did the People’s Party lose 40 seats in Scotland and hang on to just one, and only then thanks to anti-SNP tactical voting by LibDems and Tories?

“A catastrophic loss of trust,” for one thing, he says. “It wasn’t something that happened overnight. A perception of Labour built over the years as London-centric. Also trimming too much to the Tories. Labour had in its psyche the need to chase mythical middle-England voters and produced watered down versions of Tory policies. People have lost sense of who Labour is and what it’s for. This is what we’ve got to get back. In Scotland we’ve been against the SNP, against the Tories, but not setting out what we’re for. This is what’s got to change.”

Labour aligning with the Tories in Better Together was also “a big factor” in May, he says.

Did you feel queasy about it the time? “Yes, I did. I wasn’t sure it was right way to go. Labour should have been calling the shots, rather than letting Cameron, Osborne do that.”

And Jim Murphy’s contribution to the election result? He damns the former leader obliquely.

“There’s a deep yearning in Labour for more substance, for policies that matter and mean lives can be changed. This is what Labour has been lacking in recent times. We’ve had gimmicky policies to change a day or two’s headlines not designed to change the world.”

It all means the Holyrood election will be a “mountain to climb”, he admits. But he has a cunning plan to help Scottish leader Kezia Dugdale and her deputy Alex Rowley - greater autonomy to rid the party of its “branch office” label, with new rules in place from October.

In essence, Labour in Scotland would devise all policy in devolved areas, including new tax and welfare powers, but Labour at UK level would do the reserved stuff, including Trident.

“We are still a UK Labour family - I’m not talking about independence for the Scottish party - but it’s got to deal once and for all with that branch office suggestion.”

Some want a fully autonomous Scottish party, with UK Labour a mere sister party. Do you?

“No I don’t support that." That’s Alex Rowley’s idea. “Oh. That for me would be to go too far.”

Does the Scotland Bill deliver the right balance of powers for Holyrood? “It’s the right kind of balance. It delivers on the promises that were made. It’s significant extra devolution.”

But you know Rowley wants all powers transferred to Holyrood unless there’s an overriding reason to keep them at Westminster? Burnham’s not having that.

“This is where we get to a more philosophical discussion about devolution. It’s not for me just powers for powers’ sake. The aim should be to best serve the working people of England, Scotland and Wales. For instance, if you were to give more powers over the minimum wage, you could end up undermining the position of workers in other parts of the country.

“It may be old-fashioned in these parts right now, but I take the view that the cause of the working people of my region and Scotland is better served by solidarity than separation.”

Corbyn didn’t campaign here for a No vote in the referendum. Did you? “Three times, I think.”

Were you on a rota, or were you actively concerned for the union? “Oh actively. You’d be surprised how many of my constituents felt very worried. There was a real anxiety in the North West of England that Scotland might be about to leave.”

And what about Corbyn saying he’s a socialist not a unionist? Are you a strong unionist?

“I don’t agree with him when he says that. I think the two things go together. They’re consistent, socialist and unionist. Why? Because it’s about the collective, it’s about collaboration. It’s about achieving more together than we do alone. That’s what I believe in.

“For me the contradiction comes with socialist and nationalist. If your politics is about the border rather than the people, then that isn’t the politics of socialism I subscribe to [which is] about doing the best by people wherever they happen to be, whoever they are, and I feel that’s always achieved through collectivism, internationalism and, closer to home, unionism.”

Burnham worked with Nicola Sturgeon during the 2009 swine flu outbreak when he was the UK health secretary and she was Scotland’s. Did she impress you? “Yes, highly effective.”

So Corbyn’s idea of Labour and the SNP being allies at Westminster?

“I would want to reach out in terms of opposition. Our job is to do whatever we can to mitigate the effects of the Tory government. So, yes, opposition should be pragmatic and we should, where we can, work to stop the worst happening to working people. We shouldn’t be tribal.”

But working with another party in government would be “a completely different issue”.

With just two weeks to go, who’s most likely to win the leadership contest? His confidence starts to slip. “It’s difficult to say, to be honest. It’s very very difficult to call. It’s all to play for.”

But you said earlier in our conversation that you “expect to win”. Honestly? “I believe I can.”

That’s not the same thing. “No, no, fair enough. If people really think about what is at stake when they sit down with those ballot papers, if Labour goes off in a direction that takes us away from where the public are, we could leave people with two decades of the Tories. History could repeat itself and we could go back to a position where Labour was turning in on itself, and we left the way clear for the Tories to do their worst.”

For the first time he sounds genuinely pained. Not simply for himself, but for Labour’s future. The tension seeps through the neat exterior like damp, and you appreciate Corbynphobia is just as powerful as Corbynmania. It’s not simply a scare tactic to shake out votes. The heebie jeebies exist. Burnham is genuinely horrified at what will happen if the veteran left-winger takes over.

“I am worried. I’m worried about the future. I don’t think we can take anything for granted. Scotland tells us that. If we don’t get our act together, we could get damaged in the same way in England and Wales. I don’t want to see that happen. I’ve given my life to this party.”

Have you ever been this frightened before for the party? “No. In my political life I don’t think we’ve faced anything like this. You just have to look around yourself here.” He gestures to Labour’s Scottish bunker and beyond. “The tectonic plates have not just shifted, they’ve crumbled. We are in a very serious situation.”

He tries to snap himself out of it. “But I’m not gloomy,” he smiles unconvincingly. “If we make the right changes I’m optimistic we can win back people. But that’s a big if there.”