Just who is Barry Gardiner? It depends who you ask. Few outside of Brent North or Westminster would have been able to answer that question as recently as April. But now, it seems, the softly-spoken shadow international trade secretary is everywhere, manfully holding the Corbyn line in a series of fiery broadcast interviews.

His rare willingness to go out to bat for the party leadership has ended what he himself describes as a sort of self-imposed obscurity. But his idiosyncratic style – a mix of fastidious courtesy and righteous impatience – divides opinion. According to Guido Fawkes, the one-time government envoy for forestry is now “Corbyn’s media basher in chief”. According to the Skwawkbox, the excitable alt-left blog, he is “Labour’s media man on fire” – and he has “interviewers feeling the burn”.

Meet Gardiner – as I did on a sunny morning beside Wembley Stadium, in the heart of his constituency – and neither caricature quite fits. Despite making hay out of what he insists weren’t shouting matches with the BBC’s Emily Maitlis and Sky’s Adam Boulton, he is a gentle, unfailingly courteous conversationalist. Having served his time in junior frontbench roles under Tony Blair, Gordon Brown and Ed Miliband largely outside of the spotlight, he seems faintly embarrassed by his newfound notoriety. When I ask him if he could have ever expected to be the one manning the left's barricades, he convulses with laughter.

“I will fight for the Labour Party in any way I can,” he says. “If it’s been useful, me being in the media much more than I have been before, then fine. I don’t think that some of the things that are said should be able to go unchallenged. So when I see things in the media, I’m robust in my responses, they’re fairly robust with me, and I don’t see why I shouldn’t be robust back!”

And so he has - branding Maitlis’s Newsnight coverage “silly”, accusing BBC reporter Emily Garnier of reporting “fake news”, attacking Boulton’s supposedly docile questioning of Iain Duncan Smith live on Sky News, and chiding the Today programme’s Nick Robinson for reading out a Sun headline.

So does he have a problem with the media? Far from it, Gardiner insists. Some thought his eyebrow-raising interview with Skwawkbox – whose editorial line regularly flirts with outright conspiracism – suggested a certain animosity for the so-called MSM (he says he had never heard of the site, and that the request came via Labour’s press office).

On the contrary, he says that nothing can beat BBC Breakfast or Newsnight for exposure. Despite having to “hold his nose” while reading some papers, he describes himself as a media omnivore. He does, however, have a warning for his would-be adversaries. “I am absolutely cool with the media being tough. But if they’re gonna get tough with me, then they shouldn’t expect me to just roll over and have my tummy tickled.”

But despite his combative stance, he is palpably uneasy with his newfound media-basher mantle. “I have no animosity for the media. They’re entitled to ask the toughest questions of us. Obviously they have to ask the toughest of questions of everybody, and do it fairly. But I’ve no problem of them asking us tough questions. That’s their job! And thank God it is their job!”

While some have found it easy to mock Gardiner’s TV and radio bouts, if the polls are to believed, they mightn’t have been for nothing. Many on the left attribute Labour’s buoyant fortunes to election broadcasting rules which allow the public to hear the Corbyn gospel on its own terms, and few have done it better than Gardiner.

Some mock his donnish air and evangelising zeal – appropriately enough, he left St Andrew's with the intention of joining the clergy before studying at Harvard under the eminent legal theorist John Rawls – but he has undoubtedly been one of the standout performers of Labour's campaign. Surely the transition from junior minister under Blair to incongruous Corbynista cheerleader has been a strange one?

He bristles at my attempt to cast him as a factional player. His is a love of policy, not politics, he says - before noting that in his 20 years as an MP he has drunk at the Strangers’ Bar only once or twice every year. “As human beings, we’re all flawed – we’re all flawed – and that’s why I think the cult of personality is really corrosive. We have to understand as politicians that it’s not about us.”

It’s certainly true that Corbynite fervour didn’t drive him to the front bench - he did not nominate a candidate in the 2015 leadership election, though he has been studiously loyal to his leader since the botched parliamentary Labour party coup of 2016. “I’ve never been an anyista,” he says. “I’ve never been a Corbynista, I was never a Milibandite, I was never a Brownite [indeed, he was relieved of his duties as forestry envoy after plotting against the then-PM], I was never a Blairist. I’ve never seen myself as part of any group, as part of any clique – my loyalty is to the Labour Party.”

Deadpan, he adds: “That probably accounts for why I’ve been so obscure for so long.”

Whatever the result on June 8, Gardiner is unlikely to fade back into obscurity. He is, he tells me with a mirthless stare, “very confident” that Labour can pull it off. As our time runs out, he launches into a lengthy and enthusiastic attack on May’s “staggering incompetence” on social care ("she’s put policies before the public which she knows are really, really, deeply loathed – and very ill thought through"), and ends with a suitably Biblical flourish: “If that had been Labour, they’d have hounded us til kingdom come!”

The ever-narrowing polls have given him ample cause for optimism. “It’s been really exciting to see the polls narrow, and to see how the impetus of the campaign has shifted from ‘they’re a shoo-in’ to ‘My goodness! Labour is the only party that has genuinely popular policies, and the Tories are the only party coming across as incompetent.”

But he and his party still have a mountain to climb if Jeremy Corbyn is to set up home in Number 10. Does he ever fall victim to fatalism? He flashes a grin. “What is fatalism?”

And on that characteristically optimistic note, we part – me carrying a volume of Barry’s wife’s poetry for the attention of the NS culture editor, and the man himself, as unlikely as it seems, carrying the hopes of the left on his shoulders.