By Peter Ross: Set and match to world champion George, still game at 88

It would be terrible if people of our age were throwing rackets around

KINNOULL Tennis Club in Perth, the artificial grass green and brash beneath a wet clay sky. George Stewart sends a ball low across the net, and it bounces up close to my left side. My return has no power and flops feebly to the court. I think Stewart, who is 88, has decided to exploit my weak backhand.

With snowy hair and twinkly blue eyes he seems a sweet old thing, but has all the mercy of a cobra on crack. Although he is 54 years my senior, I'm panting and sweaty, and he's just dandy. If this was a proper match rather than a knockabout in the drizzle he would brush me aside like a sapling.

It could be rather embarrassing being outclassed by an octogenarian, but I don't care. This is probably the closest I'm ever going to get to playing a champ. Earlier this month, along with his 87-year-old tennis partner, Londoner Gerry Ells, Stewart won the doubles title at the Super Seniors World Championships in New Zealand. It was the second year in a row the pair have been victorious in the over-85s age group.

"That was very satisfying," says Stewart, who lives in Scone and sounds rather like David Steel. "We were playing the number one and two seeds so it was an upset."

Lorne Main, a relative youngster at 70, celebrated winning the singles title with a bungee jump. How did Stewart and Ells mark their own triumph? "Oh," he murmurs, stiff-upper-lippishly, "we had a glass of beer, I think."

Stewart is a small man ("I always thought I was the same height as Ian Woosnam, five feet four and a quarter, but I may be shrinking a bit") wearing a white tracksuit embroidered with a Union Jack. He was married, though his wife passed away a few years ago, and has two children and four grandkids. We're talking in the clubhouse next to the courts. Red light from a heatlamp falls on his face as he chats.

He plays tennis around four times each week, one of those in Stirling where he receives instruction from a coach. He is also a keen skier, and spent a gleeful day on Monday on the snow at Glenshee. "I was always interested in sport but I had a very unfortunate childhood in Glasgow," he says. "I was plagued by tuberculosis and was able to do very little. That's perhaps the reason I was so keen to play later in life."

Stewart learned to ski in Italy during the Second World War, also serving in North Africa. An agriculture student at Glasgow Uni, he was called up into the Royal Artillery, forced to abandon bucolic contemplation for years of desert fighting. He took part in the second battle of El Alamein, an important Allied victory. Field Marshall Montgomery was his commander, and though Stewart didn't meet Monty at the time, he later got to know him a bit when they holidayed in the same ski resort.

It seems some kind of chronological error, a juddering fault in the space-time continuum, that a man born in 1919, three years before TS Eliot published The Waste Land, and who served at El Alamein, could still be winning tennis matches at an international level in 2008. This isn't what we expect from old people. Their bodies are supposed to be slow-wound clocks ticking towards oblivion, their minds are meant to be hourglasses, recollections trickling through them like sand.

George Stewart isn't like that at all, and I can't help comparing him with my own 86-year-old grandad, not with any sense of disappointment at my relation, more with astonishment that Stewart is still so vivid, vital and very sharp. You could cut yourself on his frontal lobes and staunch the flow with his absorbent memory. I ask for the secret of his health. "I think it's in the genes," he laughs. "I've inherited my mother's wiry toughness. Good genes and good fortune. That's all."

He took up tennis in his 50s, has played in tournaments since 75, and is ranked 10th in the world. Stewart sometimes finds himself drawn against an old pro. He once narrowly lost to the US player Tom Brown ("The Frisco Flailer") who had reached the Wimbledon final in 1947. "It's very competitive, but polite," says Stewart. "It would be a terrible state of affairs if people of our age were throwing rackets around."

If they remain healthy, Stewart and Ells intend to visit Antalya, Turkey, in October to defend their doubles title. "It becomes harder each year, though," he says. "Even one year at our age makes quite a difference to your playing. Everything's just that little bit slower. My partner and I would find it difficult to beat a pair of 80-year-olds."

That must be frustrating. "Well, yes, but we're just so lucky to be able to run around at all. That's the only way to look at it. It's an extraordinary privilege to be able to be on a tennis court and to play a ball."

Stewart once played as part of the over-80s British team, hence the Union Jack on his tracksuit, but there isn't an over-85s team for him to join. There simply aren't enough players alive and of sufficient standard to make it feasible.

"Within five years there will be an 85s team," he insists, "and in two decades, as life expectancy increases, teams of people in their 90s will be commonplace. There is a tournament for 90s in America every year which a rich American runs. I hope to get an invitation to that if I live to 90."

If I live. One imagines that Roger Federer doesn't consider the possibility of imminent death when planning which tournaments to enter. But George Stewart has to, and I'm sure that must make each victory all the sweeter. He's not just beating the man on the other side of the net, he's firing an ace past the Grim Reaper.

So does he have any plans to give up? To quote John McEnroe: you cannot be serious. "I'll go on doing this for as long as I can, touch wood," he says, knocking the side of his head. "Too many people give up when they get old, but I want to remain as fit as I can for as long as I can. My only ambition is to enjoy what I'm doing."

That's a desire it's hard to fault.