My contribution to this summer’s modest avalanche of Andy Burnham stories extends to only two. One is about Glastonbury, and the time that he and his wife, Marie-France, came for a three-day stay at the festival, which included his appearance on the Left Field stage, organised by the songwriter and activist Billy Bragg. I help with the bookings and chair some of the debate sessions: Burnham’s was titled State of the Nation: Politics in Crisis.

It was the summer of 2022 – the prologue to Liz Truss’s five minutes in power and (somewhat amazingly) Burnham’s first visit to Glasto. As well as seeing bands – the Irish funsters Fontaines DC were among his favourites – and wandering around the perfumed fields, he had come to make the case for a lot of the stuff he has been talking about in the buildup to him entering Downing Street on Monday: “rewiring” the UK by changing our systems of politics and authority, collaborating on that task with other parties, and taking away as much power as possible from Westminster. Open, self-questioning and a talker rather than a shouter, in front of 1,000 mostly hungover people in a giant tent, he passed with honours; he was even nice to the obligatory disruptive Trotskyists.

Here, though, is the punchline, which may say something about his preparation skills, or the impossible workload of a regional mayor. The Burnhams arrived backstage full of gratitude for the chance to be there (really – they were thrilled to bits), but with a miniature beach tent they had mistakenly grabbed as they ran out of their house, which could probably accommodate a lone toddler. Bragg’s brother was kind enough to lend them his more suitable canvas accommodation.

Anecdote two: later that year, I ran into Burnham again at the Labour party conference. I explained that I had just been to review Bob Dylan in Oslo, which meant I got in for free. “Wow,” he said. “I wish I could do things like that.” I suggested that, given that one of the greatest songwriters in history was playing Manchester in November and Burnham was, you know, the mayor, one of his people could phone the promoter and get tickets for his entire family. He looked – and this is the God’s honest truth – stumped: the possibility, it seemed, hadn’t occurred to him.

Clearly, nobody gets as far as he has without ambition, self-confidence and low cunning. But people who know Burnham much better than I do agree that he can be not just humble and self-effacing but shy, and that although he has a reputation for angrily grappling with what one insider recently called “very senior people”, he is not one to indulge in rank-pulling, punching down or acts of entitlement. You hear the word “empathy” a lot.

In Head North, the book he collaborated on with the Liverpool mayor, Steve Rotheram, he wrote of his “gnawing self-doubt” about whether he would ever fit in at Westminster. He went to a comprehensive school and was raised in a working-class family in the Cheshire village of Culcheth, not far from the home turf of the singer Rick Astley. That part of the world, in my experience, does not produce many arrogant twits.

Burnham’s personality and background have definitely informed what we know of his policy agenda. Tony Blair, one of his party’s especially larger-than-life leaders – and an alumnus of Fettes College, the private school in Edinburgh – was uneasy about the politics of Scottish and Welsh devolution, as someone so full of his own zeal and power probably was always going to be. Burnham, by contrast, seems wholeheartedly devoted to giving power away and thereby weakening his own, and giving voice to what his acceptance speech on Friday called “forgotten places” who crave “a return of the Labour they once knew”. The huge expanse between Liverpool and Manchester in which Culcheth sits – alongside St Helen’s, Widnes, Ashton-in-Makerfield and good old Great Sankey – is a perfect example.

Inevitably, you can already see some of the likely faultlines in the Burnham regime, and auguries of possible difficulties to come. He not only wants to radically reshape the state and rebalance and reindustrialise the country, but to somehow roll back 40 years of neoliberalism, oversee the building of historic numbers of council houses, and all the rest: it amounts to a coherent and potentially inspirational story, with real emotional bite. But there is a profound tension between these aspirations, and some of the identifying features of Labour’s new leader.

Nearly a decade after he exited the Commons, Burnham is still a lonely figure, with support among MPs that is wide, but shallow. He has few of the identifiable signs of a weighty project: few outriders to push the frontiers of debate, and a dearth of thinkers with longstanding links to him and his people. What is increasingly glaring, moreover, are the contradictions between his radicalism, and who is meant to make it a reality: should she be appointed chancellor, Shabana Mahmood? His chief of staff James Purnell, once the very definition of a doctrinaire Blairite? The backroom Starmer insiders who look likely to stay? There is a sense here, perhaps, of Burnham’s placatory, agreeable instincts getting the better of him, and the kind of grimly comic fate once summed up by Harold Wilson: “I am running a Bolshevik revolution with a tsarist shadow cabinet.” As his most immediate, short-term priorities are revealed – binning the digital ID scheme and concentrating on living costs – other questions abound.

As he prepares to cross the Downing Street threshold, other questions abound. Being collegiate and comparatively humble might look like the right way to behave, but quite apart from the heft and determination required for his domestic agenda, how will he fare at diplomatic-cum-wartime hardball with such men as Donald Trump and Vladimir Putin? This may not be a world that suits conscientious consensus-builders and egalitarians: it may demand the rapier-like confidence and egos of big gorillas who only know how to hoard power for themselves.

And so to a more optimistic reading. If you were over, say, 10 years old at the time of the Iraq war (and, yes, I know – Burnham dutifully voted for it), you will know where puffed-up men astride white chargers have led us: into that conflict, the banking crisis, Brexit, austerity and today’s troubled world. It doesn’t happen very often, but I tried to write this piece in a spirit of qualified hope, partly because Burnham is pretty much the same age as me and most of my friends, and I would like to see him redeem the reputation of a fatalistic, blank generation, and make this country fairer and less broken. To do so while emphasising the underrated virtues of modesty, humility, actually listening to people and giving power away would make that achievement all the sweeter.

That is the prize; as the Burnham regime sorts out its metaphorical pegs and guy lines – and returns, ha ha, to the politics of the big tent – a lot of people surely feel a queasy mixture of nagging nerves and genuine excitement. So, I imagine, does he.

• John Harris is a Guardian columnist