It started with a video tape in 1986 - will it end with a Super Bowl ring?

Aden Durde's journey to Sunday's Super Bowl is not just unusual, it's unique.

Although he played professionally, he began his coaching career far from the NFL in the British amateur game with the London Warriors.

Yet he has blazed a trail all the way to the Super Bowl, breaking down barriers to become the first overseas coach to reach one of the biggest games in world sport.

As the Seattle Seahawks' defensive coordinator, one rung down from head coach, the 46-year-old has played a pivotal role in them getting to the NFL's title decider.

Speaking in California during the "madness" of Super Bowl week, the humble Briton has praised the youth coaches that "changed his life" by giving him a purpose.

Meanwhile, many he met along the way have spoken of their pride at seeing his hard work pay off, such as Super Bowl winner Leslie Frazier, one of his colleagues on Seattle's coaching staff.

"He has been able to overcome so much in the course of his career," Frazier told BBC Sport. "When I think about how he got started and where he is today, it just blows your mind. It's an incredible story."

Durde and his older brother were raised by a single mother in north London, and it was a video she bought, of the Chicago Bears' 1986 Super Bowl-winning team, that inspired him to play American football.

He played youth football in Hayes, at Finsbury Park and then in south London, for the London Olympians and London Capitals.

Some 30 years on, Durde's eyes light up at the mention of his first coach Geoff O'Driscoll. Durde followed him from team to team and O'Driscoll drove him across London twice a week, a two-hour trip each way, so that he could keep playing.

"Those people, that work as volunteers, they help kids from areas [where they] maybe don't have the funds to do something," said Durde. "They literally change people's lives, and Geoff done that for me.

"Geoff, [long-time British coach] Tony Allen, those guys are pivotal in where I am [in the NFL], but also where I am as a man. I didn't have many male role models growing up and to see these guys helping people, not asking for credit, always turning up… it's huge."

Durde was a team-mate of Tony's son Marvin Allen, and the pair have been close friends for 30 years. They both played in the now-defunct NFL Europe league and made it onto NFL practice squads.

They played against each other in Europe and for a while linebacker Durde had a picture of him tackling wide receiver Allen on his fridge.

"He was very tough and aggressive," said Allen. "He was very smart in terms of how he diagnosed plays and watched film. He was very much a student of the game."

After Durde ended his playing career, the father of two took charge of childcare while his wife Kate trained to be a midwife.

He then started a business helping children who were out of the education system and in 2011 became defensive coordinator of the London Warriors.

Yet he still found time to carry out extra voluntary work, mentoring children in north London. Durde was giving back before he'd even 'made it' himself.

"At first, it was nothing to do with professional coaching," he said. "It was doing what other guys had done for me."

Allen added: "You end up being more than just a football coach, which I think Ad was for a lot of people. He'd provide them with an opportunity if he could, but it's also just steering them in the right direction.

"It's about making sure that those around you are also being nourished and enriched. He was really good at that."

Those included Efe Obada, who grew up in foster care after being abandoned on the streets of London aged 10. When he attended a Warriors training session aged 22, Durde knew Obada could go beyond the amateur game.

He prepared him for an NFL try-out, with the pair training on public parks in London at 6am before doing their day job - Obada in a factory while Durde was now leading an NFL community programme.

"He was instrumental in my journey," said Obada, who played for seven seasons in the NFL. "He invested his time outside of the game and poured into me."

Durde was chaperoning a group of Warriors players on a trip to Texas when he got his big break.

A contact from his time in NFL Europe told him to go buy a shirt as he'd secured him an interview with the Dallas Cowboys, who offered Durde an internship in 2014.

The Cowboys' head coach was Jason Garrett, who will work on Sunday's game as an analyst for US broadcaster NBC.

"I love him," he said. "We were so fortunate, he made such a positive impression on everybody when he was there.

"He had this great balance of humility and wanted to learn from everybody, but also real strength in how he communicated and how he coached players.

"He had so much credibility because of how hard he worked and his knowledge. You weren't afraid at all to put him in situations where he's coaching players, because everybody respected him. I'm just so happy for him, he's an all-time great person."

Durde helped Simon Buckett transition into coaching and the ex-Warriors player is now the team's general manager.

"He came back from Dallas and it was the same Aden, but with more ammunition, more knowledge of the game," said Buckett. "His eyes had been opened.

"Myself and another coach would meet Aden every Tuesday and Thursday and he'd be tearing apart our next opponent, putting in new plays. We realised 'we're not going to have him very long, he's too good'."

When Durde returned from further internships in 2015 and 2016 - with Dallas and the Atlanta Falcons - he continued to work for the NFL in London, sharing an office with two-time Super Bowl winner Osi Umenyiora.

The pair came up with the idea of a programme to help international athletes transition to the NFL, effectively an American football crash-course which became known as the International Player Pathway.

Durde later ran the programme, which helped Obada get signed by the Carolina Panthers in 2017. Later that year Durde was the first American football coach to work-out ex-rugby league player Jordan Mailata.

As with Obada, Durde soon saw his potential and the Australian came through the programme before being drafted by the Philadelphia Eagles in 2018. He is now one of the NFL's best offensive tackles and won last year's Super Bowl.

"Jordan went from not knowing any of the position names to being drafted in four months," said Henry Hodgson, general manager of NFL UK & Ireland, who used to write a players' diary for Durde on the NFL Europe website.

"For Aden to have uploaded enough of his knowledge for someone to be drafted and go on to where he is now, that tells you what a great teacher he is."

It was then that Durde realised he could become an NFL coach.

"To do that from the UK is unprecedented because there isn't an obvious pathway," Hodgson added.

"The fact that Aden not only has done it, but has got to the level he's at now speaks to someone who is single minded, will figure stuff out for themselves and has the wherewithal to make something work if it's their passion or their dream."

Allen always felt that Durde, who had two head-coach interviews last month, had "the juice" to become an NFL coach.

"He has the authenticity and the communication skills, and when you have that, you can conjure belief in people," he said.

"He's a very honest person and I think a lot of people buy into that, pretty much instantly."

Durde became a full-time NFL coach with Atlanta in 2018, before returning to Dallas as their defensive line coach from 2021-2023.

When Mike Macdonald, a defensive coach, took Seattle's top job in 2024, he made Durde his defensive coordinator.

The Seahawks narrowly missed out on the play-offs in their first season but in their second they had the NFL's joint-best record with the Denver Broncos and New England Patriots. They face the latter in Santa Clara on Sunday.

NBC analyst Tony Dungy, who won the Super Bowl as a player and coach, said: "[Durde's] done an outstanding job there, and I think when you watch their defence play, you see the energy, the excitement, but you also see discipline and a fundamentally sound team. So I think it's been fantastic, and I think the sky is the limit for him."

The Seahawks' defence allowed the fewest points during the regular season (17.2 per game) and although Durde stood out as a player for his physicality, he is calm and clear as a coach.

"This is their second year being around Ad and there's a marked difference in the way they play the game from a belief and confidence standpoint," said Allen.

"They're not just getting to the ball, they're believing that when they do, good things are going to happen. It's that 2% more that takes a team from just missing the play-offs to being a Super Bowl contender.

"There's definitely an imprint of Ad when I watch the Seahawks. It's like Star Wars, you can turn to the dark side and let it eat you up. But as a leader you have to refrain and keep your emotions [in check]."

As it happens, Durde's defence has become known as the Dark Side.

The Seattle defence that helped the Seahawks to their only Super Bowl win in 2014 is known as the Legion of Boom while the Chicago defence that inspired Durde in the 1980s is still regarded as arguably the best of all-time. Now his defence has earned its own nickname.

"I love it," he said. "These guys push themselves not to replicate the Legion of Boom, but to live up to a standard, and now they're creating their own identity."

Seattle's assistant head coach Frazier was a defensive back in the Bears' Super Bowl-winning team that captured the imagination of a youngster in north London. Exactly 40 years later, they could be lifting the Lombardi Trophy together.

"It's humbling for me to work with Aden, to know how much he admired what we did, how it influenced him, and to see where he is today," he said.

"I tease him all the time. I say, 'one day, there's going to be a book written about you. There's going to be a documentary about your life'. It's just a great story."

Back in London, the Warriors plan to watch Sunday's big game together in Croydon, although Allen wants to make sure he can focus on the action at home.

"We're all very proud because what Aden's done has never been done before," he said. "When you factor in how much of a minority sport it is in the UK, in particular when he was coming up, it's amazing. There's not many stories like it, in any sport.

"It would not surprise me at all if this ends up being the story we want it to be. It's legendary. And if he can win one Super Bowl, he's going to want more."