About a boy: England's secret weapon

Theo will see it himself this weekend, as he spends time with his family before going away. The summer is not going to be easy, cooped up with a group of men he hardly knows, some twice his age. He has never been away for so long, and at 17, being homesick can still make you cry.

This is not really about football, you see. It is about a boy. A child who was scuffing his shoes in the playground at Compton Church of England Primary School not long ago, kicking a tennis ball and running like the wind. Now he is in the England squad. Tomorrow he will join up with players he used to idolise, preparing for the World Cup.

His inclusion was the breathtaking decision of a coach, Sven Goran Eriksson, who has never seen him play in a competitive match. The boy has never made a first-team appearance for his club, Arsenal. But still he has been chosen. "I was shocked when I found out," said his father, Don. His old PE teacher in Compton, Andy Colling, knew what to say: "It's real Roy of the Rovers stuff."

Like the comic-book hero Roy Race, Theo is good-looking, clean-living and level-headed. "I've had a very normal, balanced life," he said. "I don't drink and I just like spending time with my girlfriend and my family."

Ah, the girlfriend. When he said those words, the story became about a girl as well as a boy. Melanie Slade, also 17, has a smile as charming as Theo's. She was selling handbags and necklaces in an accessories shop in Southampton when they met, nine months ago, and still does, when not studying for A-levels in psychology, biology, chemistry and maths. And when not appearing on the front pages of the tabloid newspapers.

The first time was when photographers caught her walking Snoop the dog near the scruffy family semi in suburban Bitterne, Southampton. Their picture editors fell in love. "Theo's Babe" The Sun called Mel, showing her in "sexy hipster jeans" with a butterfly tattoo on her midriff. Yesterday she joined other footballers' partners at a photocall for Cancer Research UK, but all requests for interviews have been turned down until after the World Cup. Back in Bitterne, her father John told The Independent on Sunday: "I want to think things over rather than make decisions off the cuff."

Mr Slade may be his daughter's greatest asset. A former motorbike racer, he has his own PR company and once represented the gymnastics school that produced Olga Korbut, so he knows all about the pressures faced by hothoused talent. But Mr Slade is entitled to feel a little eclipsed, in what was supposed to be his own big week. On Wednesday he will become Mayor of Southampton, in a ceremony at the city's Guildhall.

Mel has a freshness about her, a childishness even, that a hard-faced, spray-tanned, Botoxed footballer's wife would die for. Coleen McLoughlin, girlfriend of the injured England talisman Wayne Rooney, is not as young, or as pretty, or as obviously clever. But she made £5m last year, through product endorsements, magazine shoots including the cover of Vogue, and a £2m book deal. Mel could make more. Even if they split up, or he doesn't set the world alight, she has made a big enough impression already. And she has been practising the lifestyle: at a school-leaver's prom last summer she wore a pale blue strapless dress ordered from New York and arrived with three of her best friends in a helicopter. Her friends are not jealous, she insists. "They're a bit shocked. It's surreal for them."

Theo has only been seeing Mel at weekends since January, when he moved with his father to a three-bedroomed flat in Enfield, north London. Arsenal had paid £5m for him (the fee will rise to £12m if he fulfils his potential). But this weekend he is thought to be back in Compton with dad, mum Lynn, his sister Hollie, 22 and brother Ashley, 19. "The response from the village has been lovely," said Lynn Walcott. "It's great to live in a little village where everybody knows you."

They talk of little else there now. "Nothing much exciting happens in Compton," says Alison Wheeler, who works in the village betting shop, "except the pub burning down."

Local legend already has it that a teacher said Theo would come to nothing and end up pushing trolleys in Tesco. The village is where he played his first game of 11-a-side football, at the age of 10. Mike Fowler, his first coach, had to run along the touchline explaining the offside rule. "His main asset is his pace, but what we later found out was how willing he is to learn."

Within a year Theo was wearing the green and white strip of big local amateur side AFC Newbury, where he scored more than 100 goals in 35 games. The club has just had to give up the lease on its ground on the outskirts of the town, hidden away on an industrial estate among car showrooms and commercial units. It needed to clear debts owed to the local council for rent, but may now be thrown out of the Wessex League. Unless it can make some money from its one-season association with the latest England sensation.

Southampton had signed him for its youth academy by the time he started at Downs School in Compton. He scored nine goals in one game for the school, but it was a rare appearance: the professionals wanted him saved for them. On the athletics track he ran 100m in 11.5 seconds.

The Arsenal training ground is beside the M25 in Hertfordshire, but the distant rumble of traffic does not drown out the birdsong. The air is heavy with the scent of mown grass and the pitches are a lush, deep green. There is something of the countryside around Compton about it, so Theo must have felt a little at home even while his stomach churned with nerves at training alongside such players as Thierry Henry, the balletic French striker who may be the best ever to wear an Arsenal shirt.

Everything at the training ground is designed to keep the players focused on their jobs without distraction - from the elegant Modernist curves of the white main building to the sign at the entrance that warns: "Players are not allowed to sign autographs. It is not their decision." So the appearance of a child among these men - mostly tall, all extremely fit and powerfully built - was confusing and unwelcome. But then the schoolboy burned them for pace, beat the goalkeeper and drew applause. He was in.

It was at this training ground last Monday that Theo played a friendly against an Irish under-21 side. The few spectators included Tord Grip, Eriksson's assistant, who had been told by the Arsenal manager Arsène Wenger that his prodigy was worth an unprecedented gamble: "He will be lethal." Theo was worried about his driving theory test that afternoon, but the game took his mind off it and he was on spectacular form. Tord made the call.

Theo was in the test centre at Southgate just after 2pm when the England squad was announced. While he was still identifying road signs, oblivious, commentators were already calling him the new Pele, the Brazilian legend who made his first World Cup appearance at the age of 17. But many young players have been compared to him over the years and been crushed by the expectation. Some of them might have gone on a cocaine and champagne binge at the news. Instead Theo played a game of World Cup Monopoly with his father and his best friend, Adam Bell, who is still a Newbury player. "I just wanted to get away from things," said the new England star. "I'm still shocked."

The rapidly formed legend is charming, but how long can he stay the same? There are reports that he has already bought a £2m home for the family in Hertfordshire. Don Walcott, a civilian administrator for the RAF, says his son is "a level-headed character". He will need to be. "Everyone wants a bit of Theo at the moment," says Warwick Horton of Key Sports, which also handles the affairs of England's next manager, Steve McLaren. It has a reputation as one of the more scrupulous agencies (which is not hard) and advised Theo to turn down Chelsea in favour of the more protective atmosphere at Arsenal.

For the agents this really is not just about about football any more. It is about Theo's potential to become an English icon. His nickname at school was Tiger Woods, because he shares the golfer's initials and something of his modern and highly marketable mixed-race look. He is cute in a way that Rooney - Shrek to even the most devoted fan - is not. And he is new. He has yet to commit any obvious indiscretions, unlike his seniors in football. If he scores goals, he could easily eclipse the £20m a year that David Beckham earns from the game and selling his image. Potential may be all Theo has now, but no England player ever had more. Seeing him, you might be persuaded that football is not a bloated game run by incompetents, in which spoilt men run wild. A schoolboy picked out of the blue and given a run in the England team, scoring the winner in the World Cup final? That would be enough to make anyone believe that dreams come true.