Labour’s campaign bus is rolling on through the outskirts of Manchester, and Angela Rayner is pointing at me with mock outrage. “Tom! What have you done to my lettuce?” I’m not owning up and insist I never even touched it. “Well, someone has done something,” she says suspiciously. The vegetable has been decorated to make it resemble the one that infamously triumphed in the Daily Star’s competition to see whether it could outlast Liz Truss as prime minister. Labour’s deputy leader decrees it needs “surgery” and a small operation is performed to replace a missing googly eye. Then the lettuce is put back in a fridge that itself has become an unlikely star of this election. It all began when Rayner told Sky News of her plan for a 5,000-mile tour of Britain on her new election battle bus, before adding, with perfect deadpan comic timing: “You’re gonna love it – it’s got a fridge.” Both fridge and lettuce have since appeared in a TikTok video filled with the kind of freewheeling spirit that’s sometimes a bit absent from the more buttoned-up approach Keir Starmer has taken to this campaign. After the bus arrives in Manchester, to be greeted by a crowd of supporters, the region’s mayor, Andy Burnham, compares Rayner to John Prescott, the former deputy leader once famed for his election bus tours. The difference this time, he says, is: “Angela has the ability to connect with people without actually punching anybody.” Indeed, in Friday night’s BBC TV debate, she was restrained as Tory opponent Penny Mordaunt repeatedly goaded and interrupted her. But Rayner knows part of her role in this election is to lighten up Labour and, sitting on the back row of the bus with her, the next display of down-to-earth humanity is never far away. At one point, she wrinkles her nose at some food on the table. “Is it vegan?” she asks. After being reassured it contains all kinds of animal products (that lettuce really is just for show) she bites into a pie. “Oh, look at that. Ham! A bit of real ham!” Rayner then opens her arms wide and describes feeling “unleashed” now she’s been cleared by the police of any criminal wrongdoing over the sale of her former council home in Stockport. But those weeks when she was under investigation have clearly been bruising. The controversy fuelled what sometimes seems like a prurient interest in her personal life and living arrangements that included getting pregnant with her first child before her GCSEs and then having two more with her now ex-husband. She thinks political opponents just “want me to stay in my lane and tell me, get back in your place”. She adds: “It’s horrible to have people telling you that you’re not all right in how you speak or conduct yourself. They try to make you feel you don’t belong. I’ve always felt like I had to prove myself. As a young mother I got the same tone from the housing department. It’s different if you have a child in your 20s but at 16, people judge you. I had to prove I could look after my child.” There was hypocrisy, she says, in the attacks on her by very wealthy men whose non-domiciled status had allowed them to avoid – legally – paying many millions of pounds more in tax than the comparatively tiny sum she was accused of dodging. “When I bought my house, I had an estate agent and a conveyancing solicitor,” she points out. “That’s what normal working people do. I didn’t have loads of tax advisers and accountants.” Does she fancy moving into another form of public housing, such as the stately home of Dorneywood, usually given to those holding the post of deputy prime minister? “I haven’t even thought about that. I love my little flat in London.” She’s not going to make the mistake of “measuring the curtains” for power when the election is not won yet and, in any case in a place like that, “it’d be quite a lot of curtains, wouldn’t it?” Rayner is at pains to deny that the obvious contrast in style between her and Starmer represents more profound differences of the kind they had in 2021, when she found out from the media that he was trying to demote her. Indeed, the steadfast support he gave Rayner when she was under attack recently has, according to both sides, strengthened a relationship which helps keep the party’s big tent upright. “We work well together,” she says, “we have each other’s backs and have a bit of banter now. Sometimes he’ll tell me I’m wrong on some issue and sometimes I’ll tell him. When you’re looking at a problem, you don’t just want yes people around you. Questioning each other is good.” Even so, there have been claims in this campaign that she’s undermining Starmer, first by publicly backing Diane Abbott’s right to be a Labour candidate, then proclaiming she wanted multilateral disarmament on the day he was seeking to emphasise Labour’s support for Britain having nuclear weapons. “Keir and me aren’t in a different place with respect to Diane,” she says, before going on to describe how the Labour leader would never have authorised the anonymous briefing suggesting Abbott was banned from standing. “I kind of know how he ticks and that’s not how he conducts himself. He’s a stickler for following the rules.” Is it true she telephoned Faiza Shaheen, another leftwinger who – unlike Abbott – has been blocked from standing? “I’m not going to get into what personal conversations I have,” replies Rayner, suddenly stiffening. On nuclear weapons, she expresses astonishment that anyone would think her remarks were controversial. “Margaret Thatcher was a multilateralist,” says Rayner, as she insists that voting against renewing Trident eight years ago didn’t make her a unilateralist. “I would sincerely hope that every leader would want a world where we didn’t have these weapons, but we now live in one where there’s Putin and we have to have our nuclear deterrent.” This is part of the serious side to her which is too easily ignored. For instance, it is noteworthy that someone seemingly as tribal as Rayner wants to have a meeting with Michael Gove – “old Govey” as she calls the levelling up secretary – about housing policy now that he has announced that he is to quit frontline politics. “I actually respect him in some ways. He identified some of the problems and solutions. He wanted to do some things on planning reform, but the Tory MPs stopped him.” Then she breaks into a smile again as she adds: “Both me and Michael like a disco, don’t we? He could pay the fiver for me to get in and we could have a disco together afterwards.” In government, there will be less room for jokes and dancing. “If we win on July the fourth, the real work begins on July the fifth. I’ve got no holiday booked for the summer. The opportunity to make change could come and go quickly. Keir won’t have us around the table if we’re not up for it.” She points out that this is the most working-class shadow cabinet in a generation. It’s not just her and Starmer, but also people such as Bridget Phillipson, who was brought up on benefits by a single mother and is “passionate about education” because “she knows what it did for her”. Rayner then pauses and looks straight ahead as she adds: “It makes us feel this real sense of responsibility. This is not a game for us.” Keir Starmer: The Biography, by Tom Baldwin, is published by William Collins (£25). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply