Barclay is the 56-year-old Australian who coached Pat Cash to the Wimbledon title in 1987 and since the beginning of 1992 has been the Rover LTA Boys' National Training Coach. Last weekend was a personal triumph for him: two of his five charges, Martin Lee and James Trotman, won the Wimbledon boys' doubles title, and a third, Simon Dickson, was the star performer in Britain's first ever victory in the Copa del Sol - a European team competition for 14-year-olds and under.
"If you'd told me when I started that by 1995 we'd be having results like that I'd have said you were crazy," Barclay said last week as he strolled through the beautiful grounds of the National Sports Centre at Bisham Abbey, in Buckinghamshire, where Lee, Trotman, Dickson and the two other members of this elite group, David Sherwood and Daniel Kiernan, attend the Rover LTA School.
Barclay is modest about his own part in this success story, but passionate in what he believes. Silver-haired and softly spoken, he has about him an air of warmth and wisdom but no mystique. All he wants - both from his boys and for them - is the best. "Even if it killed me, I could never be associated with mediocrity," he said.
Born and brought up in Melbourne, Barclay was never a big-time player, but over the years grew to command huge respect as a coach. Cash brought him his greatest glory, but when the rollicking Aussie ran into long-term injury problems in 1989, Barclay's career was stalled as well.
Like Cash, Barclay was based in London, and it did not take the LTA long to realise that here was a man worth approaching. First Warren Jacques, a fellow-Aussie, got him to help coach the Great Britain Davis Cup team of which he was then captain; then Bill Knight, who at the time was head of men's coaching at the LTA and later became a Davis Cup captain himself, asked Barclay if he would like to get involved in the Rover Junior Tennis Initiative.
Set up in 1990 with the aim of unearthing future British champions, the scheme offers specialist coaching for 150 talented juniors at centres across the country, with a handful of the very best offered places at Bisham, the boys coming under the wing of Barclay, the girls under that of Olga Morozova, the former Soviet Union player.
"I saw Bill at the Wimbledon dinner last Sunday," Barclay said, "and we both looked at each other as if to say, 'If it hadn't been for that then none of this would have happened.' It was an unbelievable challenge. But I've had tremendous support and the boys have worked incredibly hard."
Although Bisham provides a magical environment in which to grow up - a wealth of sports facilities in a setting by the Thames of 12th-century monastic calm - life for the boys is pretty tough. An average day begins with an hour's tennis lesson before they are bussed to Great Marlow School, a mile up the road. Then, when a free period crops up, they are bussed back again for further coaching. More hours are put in on the court or in the gym at the end of the day.
As the week goes on, the regime intensifies. There are no weekends. "We have a saying here," Barclay said. "Fridays is quarter-finals, Saturdays is semi-finals, Sunday is finals." School holidays are almost entirely taken up with playing in tournaments and the world-wide travelling that involves.
Guiding teenage boys through all this is not easy. "You not only have to be a great mate, you have to be able to understand their problems," Barclay said. "Because to become a superstar in this business, or to become even an average player, you have to give up so much of what normally goes with growing up. You have to work. And if you don't, you get left behind. So we have to try to create an environment where I'm not permanently driving them.
"There has to be self-motivation. We've had our ups and downs, of course. But at the end of the day it's not what I say or think. It's when they look in the mirror. Are they proud of what they see? We try to teach them that without putting them in the pressure cooker."
What pleases Barclay most about the success he has started to enjoy is the inspiration he hopes it will provide for other young British players. That and the very un-British guts and determination that Barclay's pairing showed in winning their Wimbledon doubles title when they recovered from 5-1 down in the first set to come through in straight sets. Barclay describes Lee as "laid-back and uncomplicated", Trotman as being "full of fire". And at, respectively, 17 and 16, they will still be young enough to defend their title next year.
"If they go on improving at the same rate as the last six months, anything can happen," Barclay said. That is the big question. Can success at junior level be carried into the senior ranks? Barclay acknowledges that this transition is the hardest thing of all. "It's two different worlds. Often the sense of security isn't there. But I'll still be around."
Barclay is still doubtful about the wider development of young tennis talent in Britain, sharing the view that not enough people play the game and that it is still too middle-class. And children's tennis just isn't taken seriously enough. "I've made myself very unpopular at some clubs where I've taken down the notices that say 'No children on the courts after 12 noon' or whatever. I find that attitude appalling."
Barclay, along with almost everyone else in British tennis, has had his share of critics - "the ones who told me Bisham should be burnt down. I don't know if they meant the boys should be inside at the time". But now the only flame comes from the torch that Ian Barclay is carrying.