It was August 1980, in Jesolo, Italy. Ayrton Senna, aged 20, lay in a deck chair by the hotel pool—steely-eyed, angry. He had been beaten the day before in one of the world’s most prestigious karting events, a race he had dominated until the final lap.

His rival, a British guy with a piercing mustache who won every race he competed that year (bar one where his engine blew), stood on the edge of the swimming pool, laughing and joking with his mechanic. Senna could contain his fury no more. He leaped onto his feet, stormed over, and pushed his competitor into the pool. After all, Senna hated finishing second, and of all the racers he would go onto dominate, Terry Fullerton was the one driver he could never master.

Ayrton Senna Karting 1970

Today, Fullerton, 63, lives in a small house in Leicester, England, with his wife Nilda, 11-year-old daughter and two dogs. By his own admission, he has very little money, and few people outside the world of professional karting know his name. He spends most of his days covered in oil, fingers raw, imparting wisdom to young racers as they dream of making it big. Fullerton’s talent never saw Formula One, or any race car for that matter. He made his mark on karting, proved he had the ingredients to become a legend, and then that was it.

His profile did raise when the “Senna” documentary aired in 2010. In it, an interview was played from 1993, where Senna—then a three-time F1 world champion—shocked the media by declaring not Prost or Mansell or Piquet but Fullerton the most satisfying driver he ever raced against: “He was fast, he was consistent, he was for me a very complete driver,” Senna said.

In fact, Fullerton recently received a letter from a longtime secretary of Senna’s, noting how the Brazilian F1 great talked of Fullerton as the best all-round driver he ever competed against. The reason he picked that time in 1993 to speak of his admiration, the letter said, was to do justice to all that Fullerton achieved, stating he deserved credit as the brilliant racer he was—something to that day he had never received.

And it wasn’t just Senna that couldn’t master Fullerton. He competed against the likes of Alain Prost, Nigel Mansell, Nelson Piquet and many more—and he had the measure of all of them. Fullerton was the undisputed king of karting, perhaps the greatest to have ever competed. It begs the question: if he was so blindingly brilliant, the best driver Senna ever raced against, the only man the Brazilian could never beat, then why did he not become an F1 superstar like his rivals? To understand, you need to go back to 1964, when Fullerton was just 11-years-old.

“My older brother Alec decided he wanted to race motorbikes,” Terry Fullerton told me. “He was 17, and my family were pretty straight shooters—my dad was pretty strict.”

Regardless, Alec yearned to compete, and for the next couple of years he spent all his money on bikes and racing. By age 19, Alec was living on a shoestring, barely able to pay his bills. His parents begged him to move back home, something he reluctantly did. After a few heart-to-hearts, his father decided to calm his strictness, get on board with Alec’s racing, and invest a little of his own money into helping his oldest son live out his dream.

It became a family affair, with dad preparing the bikes, and Alec soon rose to the point where he was considered a junior rider to watch, one with the potential to hit the big leagues. The Fullertons, however would soon have their world tipped upside down. The day after his 21st birthday, at a racetrack in England called Mallory Park, Alec sustained a horrific accident—one that took his life. This, naturally, crushed the family: “I was only 11, and I was at the track when he died,” Terry Fullerton remembers. “I saw him in the ambulance; it was all pretty traumatic.”

Having been to numerous races with his brother over the years, Fullerton admits that, despite the accident, by then, the racing bug was well and truly sown. He was passionate about it, a passion that somehow retained a connection with his lost brother. His father, knowing this, steered his son away from bikes and into go karts, a sport that remained considerably safer than motorcycles, where hundreds of kids were killed each year.

It was clear from the start that Fullerton was gifted. In his very first year of karting he won the 1966 British Junior Championship, a series he would win the following two seasons, rewriting history along the way.

“I must have been a bit of a natural,” Fullerton admits, speaking in a way that suggests even after all this time he hasn’t yet figured out what made him so successful. “It all came a bit too easy, to be honest.”

Victory after victory followed. He joined the International karting ranks in 1970, competing against the fastest, most experienced karters in the world—many of whom would later hit greatness in Formula One. By 1973, at the sport’s highest level, Fullerton became British Champion, FIA European Champion and then World Champion. He was simply spectacular.

This was the moment a move to race cars should have ensued—a path to stardom, financial freedom and, perhaps, Formula One greatness himself. But it never did.

“At that stage, there were three or four F1 drivers that were dying every single year,” Fullerton explains. “I didn’t fancy that at all. I suppose what happened to my brother was a catalyst to that thought process.”

It wasn’t that Fullerton was scared, but he couldn’t risk his parents losing another son to motorsports. In those days, the odds of surviving a career to F1 were stacked against you. Karting, by comparison, felt safe. People weren’t dying; the worst injury Fullerton suffered in his career were a few broken ribs. And he was building a reputation within the paddock; young drivers admired him, they looked up to him, and teams offered modest payments for his services behind the wheel. That combination meant Fullerton never tried his hand at open-wheel racing (bar a quick outing in a Formula Ford in his later years). He stayed put, stayed safe, placed food on the table and never asked his parents to deal with the inherent danger of chasing a dream in Formula One.

One young driver that looked up to Fullerton was a 17-year-old Brazilian, named Ayrton Senna da Silva. He was teammates with Fullerton at DAP in 1978—Fullerton the paid professional, Senna the paying newcomer. “I first met him when he was hanging around the DAP factory,” Fullerton recalled. “He wasn’t like a normal driver, he was very intense—a bit quiet, a bit solemn. He was very bright though.”

The team went testing in Palma, Spain, prior to that year’s World Championships. From the very first day, Senna was quick.“I was like, hold on a minute. This kid’s a bit special,” Fullerton said. But Fullerton wasn’t concerned. He knew karting inside-out—he could work on a kart better than the mechanics, he could build engines better than the engine builders, he knew more about kart design than the designers. He was incredibly dedicated to every aspect of the sport, and his confidence as a driver was unparalleled.

Senna would often be quicker at the start of a weekend. Out of the gate, the Brazilian and his mechanic would bolt on their best setup with their best engine and go for the fastest time possible. Fullerton recalls being a few tenths slower after testing, Senna smugly going back to his hotel room feeling confident that he had the measure of the Londoner. But Fullerton had been methodically working through his program, testing different things while not using his best engine, only putting all the pieces together when it really mattered.

Come qualifying, Fullerton would crush Senna by a couple of tenths, a feat that in turn crushed the spirit of the young Brazilian. “It took a while for Senna to figure out what I was doing,” he said. “It would really get to him.”

I asked Fullerton whether he believes the intense dedication Senna was known for in Formula One was in part due to what he learned from him as a teammate, but Fullerton told me he couldn’t be sure. “People close to him told me over the years that that was the case.”

Fullerton’s will to win was exceptional. I know firsthand. Back when I raced karts in 1999, he was my driver coach. He took me from a quick kid that had never won a race to a British Champion in less than a year—a kid that should have won the European Championship had it not been for someone spiking our fuel.

I remember once finishing second to Oli Jarvis, now a works Audi driver at Le Mans. It was a last lap battle between the two of us, and by a few inches, Jarvis came out on top. Back at the truck, my family and team were high-fiving, congratulating me on a great result in the first of two finals. Fullerton, however, pulled me aside.

“That was unacceptable,” he told me, sternly. “If you’re in a one-on-one fight, you must never lose. NEVER!”

A few hours later was race two. Once again, it all came down to the last lap. I was second heading into the final corner, just like earlier. But this time, it was as if Fullerton was riding with me, whispering in my ear: “You must never lose.” I found the smallest of gaps, pushed my way through, and took the win. I refused to lose. And that notion stuck with me ever since. That was Terry Fullerton. A man with a dedication to winning I’d never before witnessed. And I’ve never seen anything like it since.

During the 1978 and ’79 season, the Senna/Fullerton relationship was good. Senna often asked Fullerton for advice on his driving, and Fullerton would explain that he was “overdriving,” going in too hard, scrubbing speed on the exit with the rear tires sliding.

By 1980, however, things came to a head. Senna was then experienced, gunning for the number one position. But no matter what he tried, his DAP teammate always had the edge. That day in Jesolo was the tipping point. After Fullerton’s aggressive last lap maneuver, the pair rarely spoke again. For Fullerton, though, he never thought of Senna as his main rival.

“He was one of three or four,” he said. Someone you’d pay attention to, but by no means the only one. In 1980, Fullerton won ever single race he competed in. The only exception was at the World Championships; with a large lead, his motor blew with seven laps to go. Senna never managed to win a World Karting Championship.

In 1981, Senna moved out of karting to race cars in England. He made the jump Fullerton should have made in 1973, and the rest, of course, is history. Senna went on to dominate every series he raced, moving to F1 in 1984, punching above his weight in the lowly Toleman team, racing for Colin Chapman’s iconic Lotus team before moving to McLaren, where his epic rivalry with Alain Prost began. Prost, of note, was never rated by Fullerton in karts: “He was quick,” he remembers, “but never someone I was worried about beating me. Same with Mansell. There were plenty of other guys, like Senna, that I’d focus on more.”

What would have happened if Fullerton made the move like his aforementioned colleagues? Would that level of dominance have continued to F1, or would a race car—and the different driving style required—simply not have suited him so well?

Does he ever think about the “what ifs?”

“A little bit,” he admitted. “I’m 63, working every day, trying to teach kids how to drive go karts, and I’ve basically got no money. But the fact that he (Senna) mentioned me at the end of the film—that was brilliant. If I regretted the decision not to move into cars before, that made me think, ‘no, I don’t really regret it.’ I’ve got all the kudos and credit I would have gotten anyway.”

Senna was killed in an accident at Imola in 1994, a tragic reminder that—with the commitment Fullerton made to his parents—his decision to stay karting was probably right.