Let's begin at the beginning.
When whispers snuck out that the uproarious, splenetic frontman of hardcore act Million Dead was launching a solo folk career in 2005, there were two prevalent reactions: tattooed fanboy anguish and punk scenester bewilderment. Neither screamed 'smart career move'.
Long-term fan Zane Lowe remembers being so flummoxed by the news that the intense, yell-prone Frank Turner was taking a turn into Gordon Lightfoot territory, he thought he'd misheard.
Behind the scenes, however, there was a growing genome of faith in Turner the acoustic troubadour: both from Million Dead's label Xtra Mile, and from the singer's friend Jay (aka Beans On Toast), who, Turner recalls, "threatened me with physical violence if I didn't at least try to make it work".
These early supporters recognised that Turner was developing an arrestingly idiosyncratic sound. A scornful, mordant worldview was still imprinted into his songwriting every bit as permanently as the ink staining his forearms - as was, to a more occasional degree, his penchant for primitive, primal bellowing. But now Turner was able to couch both in sunny strums and mellifluous melody.
Seven years and four critically extolled albums later, on Friday, April 13, Frank Turner will headline Wembley Arena, where every fist-punch and vitriloic wail will be cheered by 11,000 noisy acolytes. The crowd will be warmed up by folk-punk godfather Billy Bragg and UK hip-hop favourites Dan Le Sac & Scroobius Pip... not forgetting Jay (aka Beans On Toast) - after all, Frank kind of owes him.
When we perch opposite Turner in the concrete garden of a London pub, we're greeted by his shorn barnet. He's face down, twitchingly tapping at his iPhone, through which 53,000 Twitter followers rarely go conversationally ungratified.
Turner's ego-lite closeness to his fans is one reason why Million Dead's diehard zealots have kept faith with his softer solo material - as is the continued pugnacious inspiration of Black Flag, Minor Threat et al on his fierce delivery. (Not to mention his patter: Turner spills phrases like "face-meltingly awesome" with the abandon of a man whose teenage years were forever changed by Henry Rollins.)
But just as the tatts'n'sambuca raucousness of his formative idols still bleeds into Turner's music, so now do influences less entrenched in DIY punk lore - or, for that matter, dunderheaded genre loyalty.
"I kind of got bored just making music that only appealed to angry 16-25-year-old guys in black skinny jeans wearing Against Me! T-shirts," he explains. "I say that with no disrespect, because I was precisely one of those people. But I've grown to realise that there's a disconnect within that punk hipster mindset of assuming that if lots of people like something then it must be shit. It's not necessarily true."
Cloaked in a faded Ramones hoodie, he gently speaks of his adoration for Bruce Springsteen, Warren Zevon, The Band, Ryan Adams and Johnny Cash; tuneful muses who have helped bring out the pastoral, countrified flourishes in Turner's solo work.
"I've always felt that I've made artistically valid statements - but it's more interesting to me to present those messages in a way that's accessible," he says. Turner literally and loudly applauds Kurt Cobain for "sneaking the fucking evil hardcore record that is In Utero into millions of homes that would never own Songs About Fucking by Big Black", but also admits he's pleased that his mother, a music teacher, now deems his work enjoyable.
Outside of his familial circle, Turner's slow-burn celebrity continues to grow. Wembley is an obvious career peak, whilst his team recently agreed a high-profile publishing deal with BMG. As for the next stage in this career elevation, the industry rumour mill is already crackling with news of a major label contract offer within Universal. Does Turner, a veteran hero of the independent community, feel any internal conflict?
"I've never - at least not since I became an intelligent adult - had any unbreakable hard-and-fast opinions about indies versus majors," he replies. "For a start the difference between the likes of Domino and Warner these days is increasingly closing, certainly in terms of the profile that their artists achieve.
"Also, there's something fundamentally not right about all of that indie purism. It's not as if Bob Dylan has ever been on an indie label, or Bruce Springsteen. There are plenty of examples of interesting, integral, artistic and wildly successful bands on major labels."
Turner clarifies that so long as it continues to exist, he sees no era in which he won't be putting out records on Xtra Mile, but that a "joint venture type of thing" with a major may be a possibility.
"There is no way in hell that I would have been able to get where I am today if I'd signed with a major label from the beginning - they're not particularly good at developing artists who aren't pop acts," he adds.
"That said, now I'm in a position where I don't have to compromise. I owe nobody any apologies. Never at any point in my career have I been A&R'd. The idea of having a suit with me in the studio is kind of laughable.
"I'm an ambitious person and I want to be successful. I love the indie community to a degree, but at the same time I've been fucked over by indie labels and I know other bands who've been screwed by them left, right and centre. It's not like it's the good guys versus the bad guys - it's infinitely more complex than that."
If Turner sounds more industry-savvy than your average melody-making minstrel, it's because he's read up. An avid consumer of economics books and blogs, he tackles Music Week's posers armed with expert trade terminology - from "cross-recoupable" to "mechanical royalties" - that would strike dumb even the most avaricious label shyster.
The catalyst for Turner's commercial smarts, he acknowledges, may involve proving something to his father - a City banker who previously doubted the professional credentials of his offspring's chosen career, and whose personal indiscretions have been painfully painted in song.
"This industry is my trade and I pride myself on learning the mechanics of it," Turner explains. "I actually slightly despair when I see younger bands coming through who have no idea. I long ago stopped thinking about it as being, 'Yeah man, you just play your three chords and the truth and that's it.'"
Timeworn punk class warriors might snarkily blame his bourgeoisie background for this shrewd industrialist streak - but no-one could accuse Turner of being gifted anything on a platter.
He's played over 1,180 shouty, sweaty shows across the world in the past six years - including 205 in 2010 alone. Bear in mind that the average UK employee spends just 240 days 9-to-5'ing it per annum (usually in the same comfy office, not Dan's Basement in Pittsburgh followed by a rickety flight to The Flying M Coffee Garage in Nampa) and Turner's knackering work ethic is put into stark perspective. Unsurprisingly, he doesn't own a house to call home.
"I grew up watching hardcore shows at The Swan in Tottenham," he reasons. "It pissed me off that we'd have British bands like Knuckledust, then American groups like Walls of Jericho or Botch would show up and wipe the fucking floor with them.
"It wasn't some inherent thing in American DNA - it was because you have to tour your arse off to achieve anything in the US. The American bands were playing 200 shows in a year, the English bands were playing 10.
He adds: "Of course I get tired and grumpy, but as a whole experience touring is great. I love being in a different place every day, I love meeting new people and I love the fact I'm playing music for a living: it's a fucking enormous privilege. The last full-time job I had before doing this was telesales. I was genuinely selling phones over the phone. If I ever have a shit day, I just think about that."
Turner is happy to refer to his genre of music as "English country" - but his anomalous ferocity amongst a modern trend for mild-mannered folk singer/songwriters isn't lost on him. He jokes that he's waiting for the day "a critic suggests I've snuck up on Ed Sheeran's coattails".
"I know Laura Marling and I vaguely know some of the Mumford guys but I'm not in that fucking [nu-folk] bracket and never have been," he adds. "To be honest there were times when I kind of wanted to be - but now that I've got here, I can live without it."
Our chat turns towards the Willy Wonka dream-ticket of working within this industry - and to floundering muso mates who, given half the chance, might thrive within its all-too-exclusive walls.
"Contrary to a lot of popular mythology, I do believe that most people in this industry have a core of absolute passion about music," he says. "Unfortunately there are some who don't - that breed who get a job in A&R between going to university and working for dad's bank. It's like: 'Why are you here if you don't care?'
"They are the sort of shit-heads who just have a chart music collection and a Moloko album at home. The absolute alarm bell for me is Moby's Play: sorry, but if that's on top of your CD player, you do not give a fuck about music."
There it is again: the hard-etched disdain still remnant from when "this angry adolescent found an outlet for his hate" in hardcore's snarl; back when Turner wore a homemade T-shirt that said 'SHITPOP', just to needle his Blur and Oasis-worshipping schoolmates.
This is the rowdy side of Frank Turner; the vexed, visceral ire that will turn the heads and no doubt raise the arms at Wembley on Friday.
But now he's reached 30 and those major labels have come a-knocking, could the mellow, mature Turner responsible for pretty, delicate recent efforts like Sailor's Boots and Rivers ever completely muffle the petulant punk inside?
"The fact is, I learned to sing in a small rehearsal room with everything turned up to 11 and my vocals going through a shit guitar amp," he replies.
Turner remembers one particularly indicative early solo show in Portland, Oregon: "It was in a pizzeria, so I played the most restrained, relaxed, downbeat country music I possibly could. After my set, I walked into the restaurant and pricked up my ears.
"I heard someone say: 'I liked the angry guy. I want to hear the angry guy again.'"