On an obscure tennis court just outside Athens in May last year, Jamie Baker stared at the 19-year-old Canadian kid winding up his serve on the other side of the net, and asked himself what the point was. The match was five minutes in, and Filip Peliwo, the number one junior player in the world in 2012, was pumped. It didn’t matter that this was a crappy tournament thousands of miles from home; it didn’t matter that, win or lose, the prize money would be pitiful; it didn’t matter that no one was watching. There were ranking points at stake, and the more of them he could amass, the fewer tournaments like this he would have to play in the future. Peliwo was hungry.

When Baker was 19, he had been hungry, too. For as long as he could remember, he had wanted to be a tennis player. He had given up parties and lie-ins and A-levels and home because he had wanted it so much. The prospect of 30 weeks of the year on the road, trekking from shabby hotel to shabby hotel in pursuit of his dream, was never going to deter him. But that was seven years and many injuries ago. He was 26 now. He was ranked 237 in the world. A couple of months previously he had beaten this guy easily, but that didn’t necessarily mean he was going to beat him today. I have done this so many times, he thought. I used to be like him. His foot hurt.

The match unfolded, but Baker wasn’t really there. Stiff and inhibited, he lost in straight sets to a man ranked 300 places below him. He congratulated Peliwo, and thanked the umpire, and packed up his bag. He went back to his room and wept.

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He had to get out of there. He went online and booked a flight back to his native Glasgow for about £500. He took a shower. He packed his bags, picked up his losing quarter-finalist’s prize of €215 in cash, and went straight to the airport. When he got home, he told his mum and dad what he was going to do next. He was going to quit.

One year ago this week, Jamie Baker was getting ready to play in the first round of the Australian Open after battling his way through the punishing qualifying tournament – one of the biggest achievements of his career. He had just spent nearly a month with his close friend Andy Murray at his luxurious winter training base in Miami. This time around, as Murray has accepted the Sports Personality of the Year award, Baker has been getting the Bakerloo line to his new job at Santander and working a nine-to-five. He has attended his first-ever office Christmas party. He has figured out how to use a photocopier.

At 27, the average age of a male top 100 player, Baker should be in his prime. But in the end, he just got sick of the life that he had worked so hard to make possible. At his peak, in a sport with total annual revenues estimated in 2009 at £1.6bn, he was ranked 185 in the world. Last year, the 185th best male golfer on the planet, Greg Chalmers, got about £387,000 in prize money – more than £100,000 more than Baker managed in his whole career before you even factor in his expenses. (It’s even worse in the women’s game, with smaller rewards in prize money and sponsorship alike.)

There are well over 500 footballers in the Premier League alone, and the vast majority make thousands every week. Most British tennis players, in contrast, have to lean on the Lawn Tennis Association to make ends meet. There’s no objective way of gauging who the 185th best footballer is, but it’s a safe bet that there are many Premier League footballers lower in the pecking order than Baker was who are multimillionaires; the same British public that thought Tim Henman (fourth best at what he did in the world) was a loser would never dream of casting the same aspersions on footballers who are transparently less talented – and who, by the way, don’t have to pick up their own hotel bills.

Three months after Baker took the decision to retire, I ask if he thinks this is unfair. If someone told me I was the 185th best journalist in the world, I would be ecstatic, and I would demand a pay rise. And journalism is screwed. What’s it like, then, to be a member of an elite, and yet dismissed as an also-ran? Baker, whose loose limbs, resilient tan and training shorts made him look like an athlete even in retirement, is sitting in a café near the new flat he is renting with his girlfriend in Putney – the first time he has had a permanent home of his own. He thinks for a moment. “It’s a tough one,” he begins. “For such a global game, there aren’t nearly enough people making a living out of it. Think about how many people play, how many people go to these events, how many watch on TV. And it can only support 100 or 150 players in the world? It’s crazy.”

Imagine, he suggests, that a top ten player were to lend someone like him the prize money from just a single tournament. “Immediately all the thoughts about why am I doing all this, why am I sacrificing everything, I’m not anywhere close to anything – all those thoughts have gone. You’re not suddenly going to be a world beater, but that might just free you up. Suddenly that person can go from 250 to 90 in the world and think, what I’m doing is worth it. I am bloody good at what I do.”

But that isn’t how it works. “Those were the things that really started to bug me in the last year and a half,” he says. “I had put so much into my career. But it didn’t add up. It doesn’t add up. It’ll never add up.”

By the time Jamie Baker was six years old, he knew who his hero was: Andre Agassi. He had first picked up a tennis racket two years earlier, knocking balls around at the back of the court as his mother Lynne played her regular doubles match at the local club in Glasgow. “They used to sell caps with Agassi’s ponytail hanging from the back,” she remembers. “He wouldn’t take it off. He would play tennis in it, eat in it, walk down the street in it.”

Sartorial choices aside, Jamie’s potential was obvious. The family went on annual holidays to Center Parcs; before he was ten years old, he and his older brother Steven – who would go on to play squash internationally – were winning tournaments that were supposed to be for adult guests. “They’d come on, Jamie this wee guy in his cap, or with an Agassi bandana tied round his head, and an Agassi stripy top, and you could see these adults were thinking, we’re in luck here,” says Lynne, whose gentle manner is about as far from the cliché of the tennis parent as its possible to imagine. “And then they were thinking, no we’re not.”

Jamie was soon participating in junior tournaments all over the country, which is how he first met the Murray brothers. It was Judy Murray who suggested that if he was serious about tennis, he would have to leave home and move to Loughborough, home of the LTA’s Centre of Excellence.

Lynne and Jamie’s father, Gordon, were open to the prospect – but perhaps a little overwhelmed, as well. “The first time your son turns round and says he wants to be a professional tennis player, you just think, crikey, what does that mean?” Gordon says. “If you want to help them fulfil that, you have to figure it out. But I don’t really think we knew what we were setting off on.” They and their two sons visited Loughborough, and they were impressed. With the rest of their lives thoroughly rooted in Glasgow, they visited some host families who might look after their son. They didn’t seem quite right, but what option was there? Jamie was desperate to go. “I didn’t want to board, I was too young,” he says. “But I knew it was the right place.”

On the long drive back north, they stopped off to get something to eat. Jamie wandered off somewhere, and Steven intervened. You can’t let him do that on his own, he told his parents. “And we knew he was right,” says Gordon. “So I spoke to my company, and they let me relocate down there.” Back in Glasgow, a lot of people thought the Bakers had split up. “We never thought of it as one, but it’s a sacrifice,” says Lynne. “It’s like a death and a divorce all at once.”

Although Baker was a prodigy at Center Parcs, he didn’t seem to be anything special at Loughborough at first. Even at that age, you could see the game beginning to stratify. Andy Murray won the prestigious Junior Orange Bowl tournament in Florida at the age of 12; the year before, Baker had played an overseas tournament himself and found himself “absolutely smoked” by Raphael Nadal. “I thought, that’s a bit different,” he says. “I knew I wasn’t in the top little bunch. I was one below that.”

And yet, if he knew what he wasn’t, he also knew what he wanted to be. “There was never any discussion or question,” says Lynne. “It was just what Jamie assumed he would do. When he was very young he said he would go to Wimbledon, and we would go along with it, but to be honest I thought, don’t be ridiculous.”

But it wasn’t ridiculous. He might not have had the most delicate touch, or the nimblest feet, but as it turned out, Baker was the only one of the group to go all the way. “He was so committed,” says Dr Chris Harwood, a sports psychologist who was charged with helping Baker and the others cope with the game’s taxing mental demands. “It was his motivation and hunger and discipline that were the clincher for him. And those peers of his have gone by the wayside.”

If anything, his desire was too intense: working as hard as he did, he found any external unfairness almost unbearable. “He was so totally dedicated,” says his coach, Keith Reynolds, who, like Harwood, would work with Baker throughout his career. “He ate right, slept right, cut out everything that wasn’t helpful. And after all that work, a bad line call – he felt that all his work entitled him not to have to face injustice.”

On one reading, Baker’s career is a bit of a hard luck story. If so, the first example of this came early: at 13, he had a horrendous knee injury that might have finished him. The condition, osteochondritis dissecans, meant that his kneecap was literally rotting, fragments of it flaking off and floating around in the joint. He was unable to train properly for more than a year, and as his contemporaries were hard at work, Baker was wondering if he would ever walk normally again, much less sprint around a tennis court. As his physiotherapy progressed, he sat down with Reynolds and studied videos of himself, reassembling the gait that his injury had stolen. With Chris Harwood, he stood in front of a mirror holding a racket, miming the game that his body wouldn’t let him play. When he finally got back, he barely felt as if he had been away.

He was, however, still a little clumsy. It was something to do with the intensity of his desire, according to Reynolds. “His footwork and his posture,” he said. “He was more military parade ground than martial arts. But he worked so diligently at it. Talent is a function of hard work, you know, as much as it is a genetic mix. And he would keep trying to run through brick walls. I thought that ethic would take him into the top 100 players in the world.”

The only way to get to the top 100 is to start at the bottom: the Futures circuit. Futures are to Grand Slams as the Football Conference is to the Premier League, with one crucial difference: you can’t skip them. Almost every grand slam winner has spent some time playing in Futures events, which makes for a strange mix: wonderkids in a hurry may be matched up against grizzled old journeymen eking out every last week they can from the game for fear of what awaits them when they have to give it up.

Last autumn, I attended one such tournament in Loughborough, where Baker cut his teeth. Fine facility though it is, it’s a far cry from Wimbledon. “Everyone who came to sign in for qualifying got in,” says Richard Joyner, the LTA’s Tournament Director. “In the nicest possible way, you looked up and down the courts and you could see some pretty noticeable differences in standards.”

On the first day, I’m pretty certain I’m the only spectator not personally connected to someone taking part; when I ask someone for directions to the loo, I am sent to the players’ changing room, where an early casualty is sitting in his underwear and watching Family Guy on his phone. And yet even for this standard, the prize money seems absurdly, brutally low. Each member of a partnership that loses in the first round of doubles will take home £22. Real terms prize money at Grand Slams is now about 12 times what it was in 1980; at the Futures level, it has fallen by 15 per cent.

And yet in a sense the intensity is greater. I watch two young hopefuls, Bruce Strachan and Jamie Malik, competing in a first round match that will give the victor his first ranking point – the very first step on a ladder that ends, at least in dreams, clad in black tie at the Wimbledon champions’ dinner. When Strachan prevails, his delight is no less heartfelt than you would see at the All England Club. Partly, you presume, this is borne of relief. Winning is a pleasure anywhere, of course. But there can’t be many worse places to lose.

In February 2008, Baker lay with his eyes closed in a functional Buenos Aires hotel room, and played the match of his life. The match in question was for Great Britain in the Davis Cup; by this point he had reached a promising ranking of 235, but he was playing on clay, in front of a baying home crowd, against an opponent inside the top 50, Agustin Calleri. It was a tall order. And so Chris Harwood asked him to begin by winning it in his head.

Harwood sat in the corner of the room, talking Baker through the details of the ‘imaging script’ the two of them had worked out together. As his 21-year-old charge thought his way through each scenario – where are you sitting in the dressing room? How strong is the wind? How many shots in the warm up? - Harwood hit play on his dictaphone. The noise that emerged was a tinny rendition of the baying Argentinian fans.

Baker had already been into the crucible once. On this, his Davis Cup debut, he had lost to David Nalbandian, a one-time Wimbledon finalist who greeted him by deliberately aiming balls at his head when he was stationed at the net for a warm-up rally. “The second time it happened, Jamie called the ball boy over,” Keith Reynolds remembers warmly. “He got hold of the ball, and he hit it as hard as he could, bouncing it about six feet in front of Nalbandian so that the ball was rising towards his crotch.”

This show of spirit aside, he had been beaten handily. The tie was already lost, four to nothing with one match to play. He had hardly any more right to beat a player like Calleri, several echelons above him and with a fanatically hostile crowd at his back – especially not on home turf, where he had never lost a Davis Cup match in his life. Argentina had won their last ten home encounters 5-0, and whenever Baker tossed the ball up for his second serve, the fans would barrack him as football supporters do an opposition penalty taker.

But he won. In straight sets. Five years on, in the more mundane surroundings of a Starbucks on Putney High Street, he still can’t really explain how he did it. “It was a massive, massive moment for me,” he says, dead rubber or not. “I was phenomenal that day.” It’s one of the few times I hear a little of that matter-of-fact strut so hard-wired for those at the very top: that combination of self-belief and dislocation, a certainty about your performance borne of a weird sense that it was a little out of your control – and tempered by the knowledge that when the spirit leaves you, mere talent will not bring it back. When the match finished, the Argentine fans who had been jeering throughout rose as one to give him a standing ovation.

The satisfaction that came with the victory was partly borne of a feeling that this was Baker’s moment. That match came after he had qualified for the Australian Open without losing a set, and pushed the 6ft10 20 seed Ivo Karlovic close in the first round. After Argentina, he went to the US, where he won two tournaments in a row. He hit the heights of 211 in the world. “He was on an upwards trajectory,” says Keith Reynolds. “This was breakthrough time.”

Baker’s next tournament was in Mexico. When he took his socks off for a swim at the hotel pool, he noticed a rash on his ankle. He didn’t think much of it. Then, as he did walking lunges as part of the warm-up for his first match, he brushed his knee on the ground. The contact was minimal, but within about 10 seconds, he had a swelling the size of a golf ball.

It kept happening. The slightest knock would give him a huge bruise; his gums were bleeding. He was frightened. He lost the match in Mexico, and when he got back to his training base in Florida, he consulted Eileen Evans, a cancer nurse who happened to be the mother of an American friend on the tour. She thought he could have leukemia, and sent him to hospital straight away.

It wasn’t leukemia, but the diagnosis was disastrous all the same. Baker had something called idiopathic thrombocytopenic purpura (ITP). The disease is thought to be triggered by a virus that causes the body’s immune system to turn on itself, attacking the platelets that are essential to blood clotting. Most people have between 150,000 and 350,000 platelets; Baker had just 3,000. He had to spend three days in intensive care. The disease, which affects 33 people in a million, could have killed him.

Shortly after the diagnosis, Baker learned that his recent exploits had propelled him to the heights of British number two. It was his last good news for a while. ITP was debilitating; unable to train at his previous intensity for more than a year, and with the problem exacerbated by further injuries, Baker’s ranking plummeted. His state of mind went with it, the belief that had propelled him to such heights confronted with a greater injustice than any line call. “He wasn’t himself,” says Lynne. “I thought he was depressed, and I think that’s clear, looking back. He started questioning his whole life. ‘What am I doing? I could have been dead, and I wouldn’t have spent any time with my family.’”

“Those two years were hell,” agrees Gordon. “If he’d said I can’t do this any more, I wouldn’t have tried to stop him.”

Looking back from the vantage of retirement, Baker struggles to reconcile his feelings about it. “I can’t call it a regret,” he says. “A regret is something you can control, isn’t it? But it does eat me a bit. If it hadn’t happened, I’ve no doubt that things would have been different. I would have been top 100. But then I think, I’m lucky that I’m even here to talk about it.” He shrugs. “Everyone has their story, don’t they? I would have done this, I would have done that. Those are the things that make you who you are.”

Baker thinks back to the extraordinary belief that had sustained him through those early years. “I remember being 19, winning my first title. And thinking, yeah, I can do this. But say I started again, knowing what it’s like? I wouldn’t be so confident. It’s fucking tough.”

“It’s always going to be in Jamie’s head, in our heads,” says his mum. “What if?”

If, looking back, Baker and his circle have cause for some yearning, they also seem to share an understanding that, in a life where so much is assessed by the bluntest kind of statistical analysis – win percentage, unforced errors, platelet count – it is all the more important to notice the less tangible triumphs. ITP drove him to the edge of the top 1000; it seemed to cost him his motivation and his belief. In 2009, finally fit again, he embarked on a tour of Thailand and Australia in the frightening knowledge that he needed to turn things around before it was too late.

Somehow, he managed it, putting together a run of tournaments in which he won 23 out of 25 matches, winning five successive finals and winning three of them. Perhaps the crowds were smaller, but after ten victories in a row, the string of letters in the most important column on the record of his year bore comparison with any player in the world: W,W,W,W,W. W,W,W,W,W. For a man who had been so close to despair, it was an extraordinary resurgence. “He just clawed his way back up there,” says Chris Harwood. “He was on this incredible roll. It was like the horse that’s way back that starts coming through the crowd again.”

It is a signature of the strangeness of tennis that this triumph, borne not of physical greatness but of sheer, bloody-minded determination, was experienced alone. There’s no players’ box at the ITF Men’s Future 3 event in Nonthaburi province, Thailand. Nor are there any TV cameras. On the other side of the world, Lynne Baker, incapable of sleep until the result was in, sat in front of her computer night after night, her eyes fixed on the scoreline, and her cursor poised over the ‘refresh’ button.

Thus the second half of Baker’s career began: a renaissance that featured a superb (albeit futile) performance against Andy Roddick at Wimbledon, more top 50 scalps, a rise to his career high of 185 in the rankings, and another Australian Open qualification. His parents followed that one online from the comfort of their bed, exchanging texts with his girlfriend Laura – who works in tennis herself - in increasing excitement as he edged closer to victory. When he finally did it, Gordon and Lynne cried for joy.

Lynne, who is a teacher, was so elated that she made a PowerPoint presentation about his victory and the power of belief, and took it into school the next day. She emailed me some of the pictures she used in it. Most of the time, her son is a pensive looking guy, his brow low, his natural expression solemn, the competitor’s necessary snarl always within reach. But these are different. In one, Baker is leaning back a little, his fists clenched, his mouth wide open, his eyes tight shut, the racket he has just flung away comically suspended in the air. “I love that picture,” his mother says. “He’s just radiating happiness.”

Jamie Baker never made the top 100, never won a match in the main draw of a grand slam, never made his fortune. But the recollection of those moments, fleeting as they were, endures. “It’s the spontaneous release of the most amazing excitement,” he said. “That buzz, it’s only a split second. But it doesn’t get any better than that.”

There are fewer euphoric explosions in Jamie Baker’s life today, but it has its compensations. For a start, there’s a regular paycheck. “And I never used to be able to plan anything,” he says cheerfully. “It’s so alien to me. Now Laura says, can we do this on the 21st, and my automatic response is, I don’t know, and now I think, I do know! We can!”

Laura, for her part, is relieved not to have to make the 3am drives to the airport to pick him up after a defeat anymore. But she has been careful not to tease him as he adapts to the strictures of ordinary life. “He’s never paid bills, he’s never done DIY, he’s never cooked much or done a weekly shop,” she says. “I had to explain to him that he should get a weekly Oyster card instead of a pay-as-you-go. We were at a dinner party and he didn’t know how to open a bottle of red wine. But imagine if you’d lived in hotels for the last decade. All the things you never would have done.”

As Baker points out, the tour offers its own skill-set. He is resilient; he is resourceful; he can think on his feet. He has run his own small business for his entire adult life. And there’s that intimidating ability to focus.

The last time I saw him, we met in the offices of his new employers, Santander. Baker had found the job through add-victor, a specialist recruitment agency that places former athletes in business; at the moment, as part of a rotation through departments, he is writing credit proposals for hotels and health care businesses. “It’s hard to explain how different the life is,” he said, looking a little suffocated by his suit. “My brain is tired. Everything is new.” He remembered the consequences of a recent weekend spent moonlighting as a pundit for Eurosport. (If he didn’t look quite as comfortable as the louche Greg Rusedski, his analysis was considerably more acute.) “I came back into work the next day, and I sat down at my desk. And I thought, right. This is what Monday mornings are like.”

Now that he’s gainfully employed, Baker has a bit less time on his hands. “I know you’ve got work to do,” I say. “Yeah, there is certainly a seat to fill,” he replies. So, I ask him to finish, how does he feel? Was it the right decision? “Definitely,” he says. “My mum and dad think I’m way happier. They think I’m way more relaxed. I put so much pressure on myself throughout my career. It was constant. You could see it on my shoulders.

“But,” he goes on, “it’s a difficult question to answer in black and white. Yes, there is a process of sadness. I think about all those travels and adventures, everything I shared with Keith. And suddenly I have this realization that it’s never going to happen again. There are very few people who have jobs that kind of exhilarate them on a day to day basis. And I was one of them.”

When Baker arrived back at his parents’ place after that traumatic defeat in Greece, he was certain that he’d played his final match. And they agreed that it was time to call it a day. But, his Mum said, the grass court season was ten days off. His best surface, his favourite time of year, and no need to traipse around the world. Just one more chance to play. Baker remembered something Keith Reynolds had said to him years earlier. OK, Jamie, he proposed: say you’ve hung up your racket. You’ve announced your retirement. What do you want the commentators to be saying about you? What is your legacy?

“And I knew what it was,” Baker said. “It wasn’t Greece. It wasn’t playing with fear, or nerves, holding back. It was the opposite of that.” And so he decided to have one more go.

When you go through the results, it doesn’t look like a particularly remarkable run. Success in the preliminaries in Nottingham and at Queens, and then defeat in the second round of Wimbledon qualifying, denying him a final shot at a grand slam victory. Anyone who wasn’t watching him closely would have noticed it. But playing in front of his family and friends, and knowing he would never do this again, Baker felt different. “I was playing in this way that was so relaxed, so uninhibited,” he said. “It was what I’d been trying to find my whole career. And I hardly stepped on court to practice. It was just… there.”

His father and his girlfriend were in the crowd for his last match, against Igor Kunyitsin, a Russian baseliner who had once been in the top 50. It was a fine June day, and the match went this way and that. Laura felt the sun on her, and watched him take the second set, playing with the joy that he’d always been seeking. “And the beautiful blue sky, and the grass, and all these people who’ve helped him over the years,” she remembers. “And you just think, how can you ever give it up?”