One of the enduring mysteries of sport is why one child who looks a world-beater at 12 goes on to become a taxi driver while his friend, who may not be quite so promising, matures into a legend in his own lifetime.

Over the past 20 years, Ben Ainslie has pushed himself probably as hard as any British athlete to achieve the success that has come to him. It is no exaggeration to say that, at 32, he already enjoys legendary status in sailing by dint of his four Olympic medals in successive Games, with one silver and three consecutive golds in two different classes of boat.

But why has Ainslie got so far? Over the years that we have come to know this shy and modest individual who first graced the Olympic stage at Atlanta in 1996, we have seen and heard about his focus, his determination, his unrelenting will to win, his ability to perform under pressure and his habit of never giving up even when struck down by illness or rotten luck.

But there has always been something missing - a piece of the jigsaw that Ainslie has kept to himself. Until now. That missing ingredient is what happened to him at school and it is something that Tom Daley, the world champion diver, knows all too well about - the curse of bullying.

In Daley's case, the mocking playground chants of the jealous have driven him from his chosen school but they do not appear to have affected his self-confidence, warmth and development as an athlete.

While Daley appears to have been bullied because of his success as a budding diver - being called “Speedo” and “Diver boy” - Ainslie was picked out for a different reason. From an early age he suffered, and still does, from a photo-sensitivity of the skin that manifests itself in blistering and rashes. Going to Treliske School in Truro, Cornwall, at the age of 8, the rash would often appear on his face and the young Ainslie was made to pay the price.

In his recently published autobiography, the man who now drives an Aston Martin, and leads the Great Britain America's Cup team, writes with extraordinary candour about experiences that have scarred him psychologically for life - but, remarkably, not wholly in a negative way.

Rather than allow the bullies to destroy him, the young Ainslie, who was extremely shy to the point of being withdrawn, determined that he would use the experience to spur him on and it has proved a powerful tool.

“Unfortunately, it began at my first school and continued through to the main school as I stuck with the same pupils over a seven-year period and they never really gave me a break,” Ainslie writes in Close to the Wind. “Like all things, the teasing came and went, but I guess it did have a profound effect on how I developed. It made me ferociously determined to be good at something, to prove to myself that I could be a success and that there was more to life than school and being picked on. Sadly, it also meant that I found it hard to trust people, was very defensive and found it very difficult to open up to people emotionally.”

Clearly, the positive energy and determination that Ainslie derived from being taunted was a huge driver in a child who, at the same time, was showing an exceptional gift for sailing and developed quickly from local racing in Falmouth to national and international competition. But there is no doubt, too, that the “ferocious determination” has been on display for years.

A striking element in Ainslie has been his consistency of purpose, certainly from the age of 18 when he was first selected for the Olympics; he has never wavered, never gone off the boil and never deviated from his goals - winning Olympic golds and winning the America's Cup for Britain.

At times he has struck his friends as being fanatical and obsessive, pursuing his sport at the expense of further education and his social life. He has never allowed himself any quarter, any excuses for losing or much time off and he has little sympathy for those who put less work and graft into their racing than he does.

Ainslie has driven himself from one achievement to the next and admits that within days of winning gold in the Laser class at Sydney in 2000 a voice inside him was asking, “What next?”

One can only wonder what those who mocked him at school think of him now, and what they have achieved while he has gone on to scale the highest peaks of his chosen calling.

“Thankfully, I had sailing to lift my spirits away from school,” Ainslie says. “It made me so determined to do well. To have a sport like that, which I was really good at, was my way of giving myself confidence, proving to myself that I could do something.”

Close to the Wind is published by Yellow Jersey Press and is on sale for £18.99.