It's the middle of December, 10 days away from Christmas. I'm on a train chugging along the south coast of England, across chilly countryside under a darkening grey sky. It's almost idyllic but mostly bleak, and so very ordinary - I've watched industrial estates and small villages like these roll by a hundred times before. This isn't where you'd normally go looking for a superstar.

Bournemouth station is my stop, a seaside town with nice Victorian buildings and lots of students. Many of them study at my destination, the Arts University of Bournemouth, where I'm about to meet the course leader of acting. His name is Doug Cockle, but you and I know him better as Geralt of Rivia.

Cockle looks like a teacher, like every teacher you ever saw walking around a campus or school corridor. Nothing marks him as extraordinary. He's middle-aged, a bit shorter than me and wears sensible glasses. He's dressed comfortably rather than showily in plain, warm, everyday clothes. His hair is shaved and he has a slight beard. He does not have a mane of flowing white hair.

He isn't gruff, either, or arrogantly aloof. He is mild-mannered and friendly. And as we walk to an onsite cafe for a cup of coffee we make everyday small talk about students leaving for Christmas and oh my isn't it getting cold. He buys me a coffee with a handful of change from his fleece pocket. It is an entirely unremarkable situation.

Then I hear his American accent, half growl, half purr, and I remember who he is, like it's some kind of secret, like he's wearing some kind of disguise. I realise I know, and I'm not the only one.

"I don't know when people really clock," he says, "some of my students I think still don't know. I do share it when I'm recording something; if the students ask, I'll tell them. But I was supposed to be very tight-lipped about The Witcher 3 so I didn't say a lot about it. I got told off once for just tweeting. But the ones who were listening knew.

"There are some students who I talk to regularly who I can see getting starstruck, where they kind of go a little funny, a little awkward, and they don't quite know how to talk to me. It's almost like they're scared to approach me about it, or they feel like they don't want to cross a line.

"But one of the things with voice acting is it's the voice people make a connection to, not the face, not the whole person, whereas with film and television we make a connection with a person because we're seeing a person. With Witcher 3 they see Geralt and they hear my voice, but they attach that voice to that other image. It's a weird separation of actor and audience."

But here is someone synonymous with a game and series at least as successful as anything Troy Baker, Nolan North and Jennifer Hale have appeared in. He's video game acting royalty. Can you imagine The Witcher games without him? Because that was very nearly the case. Had destiny not placed a talkative friend where it did, I wouldn't be speaking to Doug Cockle today.

Cockle as Captain/Father John Maloney in 2001 television series Band of Brothers.

Doug Cockle didn't always want to be an actor. He was born into a military family in 1970 and grew up in Twentynine Palms near a US Marine Corps base where his father was an officer. His mum was a teacher, his dad dabbled in art, but neither of them were theatrical. "I wanted to be a helicopter pilot, or raise dogs in Oregon," he says now we're settled in a small white room in the drama wing of the university. He quite fancied studying wildlife biology like his dad. That interest turned to medicine and a place at university as a biology major after he read about gene manipulation curing diseases in unborn infants and thought it was a brilliant idea. But he couldn't get the grades.

It was then Cockle turned to theatre, where most of his friends were and where he was spending most of his time. He had put on shows for his parents, with his sister, when he was growing up, so perhaps it was a lingering desire that led him there. He doesn't know. Point is, he went, he made "a wild leap", and he landed with a theatre degree from Virginia Tech in 1993.

From there he moved to Seattle to make it as an actor, worked the fringe, recorded adverts - good paid work - and took on a variety of day jobs, as actors do, to support it all. One of those was in a little shop in Seattle's historic Pike Place Market, Mug's Antiques. A lady came in and bought a paperback book. "We got to chatting. I suggested she just bring the book back when she was done and she could get another. She did... several times," he says. It led to coffee, to a walk in the park, to one thing, to another, and marriage.

Three years later, Cockle and his wife moved to Pennsylvania so he could study for an MFA in acting. The obvious next step, for an actor, would have been the bright lights of New York or Los Angeles, but Cockle wanted an adventure and his wife missed her parents, who were in the UK (she had once lived here too). So it was decided: go back to the UK for a year. That was 17 years ago.

They moved in July 1999 and almost instantly Cockle got a break, "blagging", as he puts it, a role alongside Honor Blackman at the York Theatre Royal. It got him noticed, and he landed an agent. And the agent landed him both a role on the Band of Brothers television show and an audition for a video game voiceover. It was October 1999.

"It was all very exciting but I knew nothing about voiceovers for video games," he says, "I didn't even know that they existed. I went along to this little studio that was built into the side of a house on a hill in Harrogate up in Yorkshire, for a game called Independence War 2: Edge of Chaos, and I auditioned for the main role, Cal, and got it.

"That," kids running around half-naked because the family's living room was next door to the studio, "was the beginning of voiceovers for games for me."

Cockle as Larry in Burn This at the Duke's Theatre Lancaster, year unknown.

As chance would have it, Cockle had gotten in with the right company at the right time. Those kids belonged to Mark Estdale, whose fledgling Outsource Media company has been at the forefront of UK video game sound recording ever since, albeit now residing in London rather than on the side of house on a hill. Estdale gave Cockle a lot of work. Indeed, it was Estdale who phoned him about The Witcher.

By then it's roughly 2005. Not only is Cockle an old hand at video game voiceovers, he's appeared alongside Pierce Brosnan and Geoffrey Rush in The Tailor of Panama; alongside Christian Bale and Matthew McConaughey in Reign of Fire; and landed a job at Arts University Bournemouth. Not to mention the theatre and radio bits in between. He's been busy, as actors tend to be.

Cockle heads to London and meets a man called Borys from CD Projekt Red. That's Borys Pugacz-Muraszkiewicz, who was then a lead translator, now a lead writer, and has always been a key person for Cockle. "He's the one who suggested that I think of Clint Eastwood in Dirty Harry as an example of the kind of thing they wanted," he says. "I think I spent about 15 minutes in the booth playing with things and then I headed off." A couple of weeks later he gets the call; he's got the part.

"It was work as normal" Cockle says. Up to Outsource's old offices in Sheffield on the train for a week. Nothing seemed out of the ordinary. Except, well, he does remember there being a particular excitement about the three or four Polish people there, and when they handed him the script and he thought the game sounded like fun.

"We spent a week, four or five days, [recording]. And they were long days," he says, "some of those days were 10 hours, which is a long time to be doing any voice work. It was hard. It wasn't painful or anything like that but it was a challenge. It was an intensive time. And I remember thinking 'this is going to be a big game'. There was a lot of dialogue."

Then just like that the job was done. He says goodbye and thanks for the lunches and heads back home. Life carries on. He doesn't even realise when The Witcher came out in October 2007, just like he doesn't realise casting has begun for a second game until destiny intervened.

"I didn't know Witcher 2 was even happening until one of my actor friends said, 'I went and auditioned for this game the other day, Witcher 2, didn't you do Witcher 1?'

"I said 'Yeah, who did you audition for - was there a particular character?'

"He said 'Yeah, Geralt, didn't you play Geralt?'

"I said 'Yeah, I did!'

"Oh it felt rubbish!" he says, to know they were casting but he hadn't been called. What on earth had he done wrong?

But an actor is nothing if not tenacious, so he brings up Borys' number on his phone and sends him a message, plays it cool, says he's heard there are castings and could he come in. And Borys replies.

"What happened," he says, "is between The Witcher 1 and The Witcher 2, CD Projekt decided that they wanted to completely shake it up. They were pleased with how Witcher 1 had done but they wanted to recast everything, go with a different voice production studio. I don't know why; their reasons were their own. But that's what they decided to do."

Borys apologises and goes to see the new voice director for The Witcher 2, Kate Saxon, and mentions Doug Cockle. "And the story is that they went back and listened to some of the recordings from Witcher 1, and Kate went 'Actually he's really good - that's a good voice for Geralt. If you're happy to bring him back I think we should just do that.'

"It was almost an accident that I ended up doing all of Geralt in all three games."

Cockle as Goosh in 2002 film Reign of Fire.

The Witcher 2: Assassins of Kings was recorded at a different studio, called Side, and in London. The whole production was bigger, from game to organisation, everything. Our returning hero, Cockle, walked in a little afraid.

"I was pleased to be asked to do Witcher 2," he says, "but, I'll be honest, when I went in for the first session I was very nervous because of what had happened. Even if you know it wasn't a personal thing, that you had done a good job previously - which I did know because I was told that - it shakes you. You begin to question, 'Well could I have done something differently that would have made them think differently between the two games?' So I did go in very, very nervous."

But as time rolled on, Cockle found his groove. He even found room to inject some humour and emotion into Geralt this time, to humanise him. "I remember the troll storyline and thinking it was just silly," he says, "and that was good, that was a good thing, because CD Projekt wasn't taking themselves quite so seriously. It was nice to see some humour creeping in." Ditto emotions, something CDPR kept "a hard rein" on before. "In Witcher 2 they started to allow that."

On the last day of recording the team goes for lunch and then goes their separate ways. This time he had hints from Borys about The Witcher 3, that it was coming, though the thought "gosh I wonder if they're going to do a similar thing and want to shake it all up and move things around" did cross his mind.

May 2011 comes around and The Witcher 2 is released. Cockle waits with anticipation for the reaction to his performance. And keeps waiting. And keeps waiting. "Nothing," he says. "Nothing at all. There was almost no interest in me whatsoever."

A little deflated, he checks Amazon reviews to see what people think. "And someone," he says, "said something like, 'Yeah it's great but the guy who plays Geralt sounds like a 16-year-old trying to do a 42-year-old's voice,' or something like that! And I actually was so pissed off about that I got on and replied and said, 'Actually, I am that age - and I disagree. It is my voice and go stuff yourself!'"

Cockle as Lincoln Mathers in 2004 film London Voodoo.

"By the time we got to Witcher 3, I knew Geralt," he says. Cockle knew him from Andrzej Sapkowski's books, by now available in English - he's a big fan, "loves" the Tower of Swallows - and knew him from two games and the shared plotlines for the third. He even watched the ropy Polish Witcher television series. "It wasn't great," he says, "but it was OK."

The voice was also by now second nature, "bedded in", he says, whereas in The Witcher 1 it was "a very conscious effort" to maintain. "If you go back and listen to Witcher 1, Witcher 2, Witcher 3, you will hear a difference in terms of performance, but I don't know how much of that is [on purpose]. My voice changed," he says. We are talking about 10 years of someone's life here, and he'd quit smoking during The Witcher 2.

"Going into Witcher 3 was like slipping into a comfortable bath," he says - exactly how Geralt starts The Witcher 3, coincidentally. Cockle knew the team, the studio, the character, the voice, the world. "It was really nice to go back in."

Funnily enough, though, Cockle barely knew the rest of the cast. "It's very rare for actors to record together for games, partly because availability for individual actors is often very hard to gel. I've always recorded alone in the booth for Geralt," he says. "We're like ships in the night. Sometimes I meet people as they're coming out of a session and I'm going into my session, and we'll run into each other in the hallway, but even then there were only a very few of the actors from any of the Witchers that I actually met."

He met Triss, Jaimi Barbakoff, but he never ever met Yennefer, Denise Gough, although one afternoon he came close. He'd been to see Gough in her starring - "brilliant" - role in West End production People, Places and Things. "I went to the stage door because I was going to introduce myself and say, 'Hey great job saw the show and by the way I'm Geralt,'" he says.

"But I waited by the stage door, I waited for about 15 minutes, and thought, 'You know what? She's probably taking a nap.' Her performance was so intense and there was another show that evening, so I left her to it."

Ships in the night. Odd though, considering the moments Geralt and Yennefer shared on the screen, on a certain unicorn. But even those moments, the sex scenes, are handled alone - pun, I'm afraid to say, intended.

"It's like the violence," he says, "the hit that the character takes, the damage that he or she takes. You have to do a reel of different intensities, different kinds of injuries, different kinds of screams, different kinds of dying - you have to die different ways. It's the same for sex; you have to enjoy yourself in different ways. What is that other character doing to you? What noise does that make you make? It's... interesting!"

And a bit embarrassing.

"It's one thing if you're doing a love scene, any kind of real intimacy, on stage or screen," he says. "It's easier to do when you have someone there you can do it with. That's natural, that makes sense. It gets awkward when you have to negotiate 'tongues, no tongues?' but there is a negotiation that happens silently or verbally.

"When you're doing it in the booth there's a different kind of awkwardness, because it is a bit like masturbation, you're being caught masturbating. Do you know what I mean?"

No! I mean what?! I mean do you know what he means?

"That's what it feels like," he says. "If you can imagine yourself having a good old wank and in walks your mum. It's that kind of embarrassing feeling."

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"We're still early days in terms of people fully appreciating the contribution that the voice actors make to the games," Cockle tells me, topically.

"It's a funny thing with games because the voice actors, no matter how big we think we are, how important we think we are, we are a very very small part of the overall development process of the game. There were hundreds of people working at CD Projekt on Witcher 3 in various capacities. They're not being brought in for three days a week for a month: they're there every day for five years or however long they were there slogging away getting this thing put together.

"The developers are the stars of the games industry. Where film, the production company is much more behind the scenes - the focus is much more Tom Cruise or whoever it is; in games, the focus is the game and the people who've developed the game. Voice actors are just a part of that. One part of it. One part among 30 parts.

"What I'm trying to say is, I was expecting to get a different kind of attention from The Witcher 3 than I'd had from anything else, but I was surprised, eventually, how much attention I've had. And at the same time," he says, "I'm also surprised at how much attention I've not had, but I don't know why I say that - perhaps it's my ego, the actor's ego."

Cockle prepared himself and his wife for The Witcher 3 opening doors, maybe even relaunching his full-time acting career. "I knew The Witcher 3 was going to create a stir I would not have been able to generate otherwise," he says. But besides recording several roles for Sony's upcoming PlayStation 4 exclusive Horizon: Zero Dawn, it hasn't really happened. Not yet.

"It's definitely changed my life in a number of ways, some intangible and some very tangible," he says. "A simple little thing: the money I was earning. You have to understand that while The Witcher's happening I'm doing other things as well. I have a small role in [the film] Survivor with Milla Jovovich, I have a small role in the Kevin Costner film [Criminal] that just came out. I've been doing other games. It's not just The Witcher.

"But The Witcher being what it is, being the big one of the last few years - of the last 10 years really - the extra money has been nice. I'm not rich by any measure but it's allowed me to do a few things that were perhaps a bit frivolous and fun that I might not have done had I not had that extra money. Things like I bought an electric guitar because I've always wanted one. ﻿I wouldn't have done that if I didn't have some extra Witcher money on the side to go, 'You know what? I'm just going to go spend £500 and buy a guitar!'"

Another major plus is Doug Cockle gets to say he's Geralt of Rivia. "It's fantastic! People love the game, love the character and they contact me on Twitter and they say, 'Just wanted to say fantastic job! Love your voice, love what you do with Geralt, love the game!' And it's nice, that's a really nice thing."

He's been nominated for awards, won a NAVGTR award, and there could always be more. He's been to the BAFTAs, been to the LA Game Awards. "That's all really brilliant stuff," he says.

Doug Cockle as I see him before me now, 15th December 2016.

I sense that he's waiting, coiled ready for an opportunity. "It's not happening now, and I don't see something coming in that regard but it's entirely possible," he says, he hopes, "because when you get that kind of attention, people notice." But at the same time he's torn, all too aware of the real toll recording The Witcher 3 took, in London half the week and working around the clock at University the rest. "It was putting a serious strain on my personal life," he says. "And I'm not saying I wouldn't do it again, but I'm aware now, ﻿having come through it, of just what an effect it was having.

"I don't know..." he ponders. "﻿If an opportunity came up in video games or in television or film, something big that was going to mean a big paycheck and a lot of work then I would have to consider that very carefully, but I can't just take a leap into the unknown and risk the stability of my family on a complete gamble."

His teenage children are happy where they are, his wife is happy where she is. They have a comfortable life. "﻿The extra acting work that I do," he says, "whether it's a lot of work or a little bit of work, ﻿is part of feeding my soul."

If he chased the dream he would have to travel a lot, probably without the family (he was away in Ireland for three-and-a-half months filming Reign of Fire, albeit before kids), and there would be no guarantee of work, of income. "It's not a healthy situation," he says. And unlike Troy Baker and Nolan North and Jennifer Hale, who he admires, he says, "I'm not very good at playing the game."

The Witcher 3, though, he has played. "Yes all the way through," he says. "I even got the ending I wanted." And Triss, if you're asking. ﻿"You know," he adds, "I have a sneaking suspicion that not all those grunts are mine."

Maybe Geralt of Rivia is Doug Cockle's crowning achievement, perhaps those days of galloping around the globe chasing fame are for someone else, someone singler, someone younger. It doesn't really matter, it's still a towering achievement; The Witcher 3 shows every sign of going down in gaming legend. CD Projekt Red may even bring him in again for Cyberpunk 2077. He's certainly game. "Absolutely!" he beams.

"I have joked with them about bringing me in as an Easter egg. I've jokingly said, 'You've gotta bring me in as a bartender the player has to interact with for at least one quest. A bartender named Gerry who has some waiting staff... Trisha or Jenny or something like that.' ﻿But who knows? They may... I hope they've enjoyed working with me and bring me into audition for characters in that, we have a good working relationship. But the industry does what it does."

It's dark by the time I leave Doug Cockle. He calls me a taxi and waits by the road barrier with me for it to show up. It's cold, maybe even raining. I'm so wrapped up I can't tell. Like so much else today it's an ordinary scene, two acquaintances stretching out a goodbye. In so many ways Doug Cockle is an ordinary guy, no glitz, no glamour, no razzamataz. But what he's done is anything but ordinary, so for your extraordinary work and story, Doug, I thank you.