“I just want people to see that I’m a normal person.” It’s a simple aspiration for most, but for a character as unusual as Shaun Smith, it’s an ask that gets larger the more you learn about his life and past.

Let’s ease in with the obvious oddities: the man looks like Paul Hollywood. A beefier brother of the Bake Off judge, perhaps, but the similarity is ridiculously uncanny. “A lot of people say [we look the same], but if I had his money I wouldn't be doing what I’m doing,” chuckles Smith in his thick Scouse accent. “Paul Hollywood beats eggs. I beat people.”

He’s only partly joking: 51-year-old Smith now works as what one Vice documentary dubbed “The UK's Scariest Debt Collector”, exercising his talents of “persuading people to hand over what’s owed,” as he puts it. It’s not exactly something you can see Mary Berry lending a hand with.

Yet what’s even more intriguing than his current job is how he got it: it’s a profession rooted in his past role as a drug dealer’s enforcer, a life that led him into the violent heart of the mob world, five years in prison for a firearms offence, and even a narrow escape from a car bomb planted by a rival gang in 2003.

Although Smith says all that is behind him and that his current debt collecting company (complete with polished website) is all “legit”, his past life could soon be on screen. The makers of Netflix’s Narcos are currently in negotiations to bring a gritty drama series based on Smith’s life to TV, with two seasons currently mapped out. 

The scripts have got Smith’s blessings, even if he’s miffed by the writers’ approach: “They kept saying I was like an English Tony Soprano, and I said ‘you taking the fucking piss?’” Smith laughs. “I’m just a regular guy with a talent for collecting money off people.” 

But it's not Smith’s criminal past that’s landed his most recent round of media attention. Thanks to his latest role as the UK’s top bare-knuckle boxing promoter – organising and refereeing bloody bouts over the past six years – he’s the central subject in Channel 4’s Bare Knuckle Fight Club.

Filmed over the course of a year, the documentary got its crew ringside seats in venues across the country where Smith’s muscled fighters ditch the gloves and take a volley of knuckles until they surrender or come out victorious. It’s a world where jaws are crunched, minds mangled and, most crucially, identities forged.

As the one-off film investigates, bare knuckle fighting isn’t an outlet for lawless psychopaths on the lookout for a bust up – it’s also a way for men to earn meaning in a shifting world. 

“Young lads often plead to be put in the ring, saying ‘I just want to be a man and get a face full of fists’. It’s just the alpha male in everyone coming out,” claims Smith. “Everyone loves a bit of violence. We all fucking stem from cavemen, don’t we?” 

And with fighters ranging from solicitors to soldiers, he argues that knuckle fighting is blind to class: “It’s easy for society to say ‘oh, it’s just lads who can’t get a job who fight’. But these are lads that just want a bit of excitement. We don’t grab these people and throw them in the ring and tell them that they’ve got to fight. We advertise what we’re looking for and people come forward. Nobody’s got a gun to their heads. They want to do it!

“That’s why I did this documentary: I want to show the public that these aren’t fucking animals," he continues, raising his voice slightly as his passion kicks in. “I wanted to show they’re not fighting in the gravel. They’re in a ring with paramedics and doctors on the corner. A long time ago we had pub fighters, but we do everything professionally now. Even the people that put the bandages on the fighter’s hands have to go on a course!”

Still not convinced you’d get your kicks witnessing two men hammering their fists into each other’s eye sockets? You might be surprised. Ed Perkins, the documentary's director, admits he couldn’t sleep for several hours after filming his first fight due to the adrenaline rush. “Like most people I’d never been to anything like it in my life, but I was captivated by it,” he told RadioTimes.com. “Yes, it was so brutal, but I had so much respect for people who go out there. They have a lot of bravery.”

However, courageousness doesn’t help heal the damage from an uppercut to the head. Years of fighting in the mob have taken their toll on Smith’s mental health, with the debt collector-cum-promoter suffering just as much as the 85 fighters he’s trained: doctors prescribe him 75ml of meds a day to battle psychosis and panic attacks. And Smith makes no secret of this: “I have battles every day with myself. It’s like that saying we have in bare knuckle: you can mend broken bones, but you can’t mend broken brains.”

It’s this disarming honesty that makes Smith so engaging, his history and current dealings are open to all – including law enforcement. “The police come and visit me every two months asking if I’ve been knocking on somebody’s door, harassing them,” admits Smith. “I say ‘Yeah! I fucking am! Somebody rips off somebody else and our legal system lets them get away with it!’”

And it’s here where Smith’s law of talion blurs the line between vigilante and outright criminal. While the violence in the ring can be seen as a place of belonging for partakers, his day job veers deep into the moral wilderness.

In a clip that won’t be aired in the UK (but will in the FX’s three-hour version of the film in the US), a debt-collecting job spurs Smith to a confrontation in a pub with an unidentified man who allegedly in the past assaulted his parents and robbed a children’s cancer charity. “I gave him a few good slaps,” Smith says proudly. “And if I didn’t know I was on camera I would have given him a good kicking too.”

Bare knuckle fighting has willing participants, debt collecting has definite victims – no matter how deserving he sees them. Yet despite this, Smith says there’s nothing massively intimidating about him: “No, I’m not dead violent. Look, if people want to be violent with me then I’ll be violent back. If people want to be nice then I’ll be nice.” 

It’s a statement that makes answering the central questions of this documentary so difficult: does the bare knuckle violence encourage violence outside the ring? Is Shaun Smith a good person? And, most importantly, does he deserve forgiveness for his past?

Fortunately, Smith gives us an answer to the latter: “I don’t want forgiveness, I just want people to understand. I want people to know why I’ve done what I’ve done. I didn’t just wake up one day and think ‘see, that lad there, I’m going to punch his fucking head in’. In my eyes, no innocent person has got hurt. I did to them what they did to others and I want people to see that that was just my job.

“People might think something different about me, but they don’t know me. And if they don’t then I’d say come and sit down and have a chat with me and you’ll see a different person.”

And if you ever come across the enigmatic Shaun Smith, we recommend it’s an offer you take up. Just make sure you don’t owe anyone money first.

Bare Knuckle Fight Club is on Channel 4 at 11pm on Wednesday 29th March