'The trouble with those sort of people is they've got no garden of their own, so they've no idea how to behave in other people's gardens.' I exit, pursued by the bear of her certainty

Emily, a friend from two doors along the terrace, phones on a hot Saturday morning. Her neighbour, Wes, a quiet, dignified, middle-aged West Indian, has had all the apples ripped from his tree and thrown around his back garden; his neat rows of lettuce and spinach seedlings have been trampled.

"He's not angry," she says, "just devastated. We must find out who did it." We summon Jacob, five, who sometimes plays with kids from the surrounding houses - they squeeze into one another's gardens through gaps in the fences. "Did you see anyone in Wes's garden yesterday?" Jacob is strangely silent. "Were you there?" He looks at the floor. "Is that a yes or a no?"

"Yes!" he says with embarrassed annoyance. "Did you touch his apple tree?" Silence. The kitchen tap drips. "Jacob, did you touch it?" "Yes!" "What were you doing? You know you're not allowed in there."

"Shooting."

"Shooting?"

"The boys were there. I was in the garden and an apple zonked me on the head. I just had to join in."

We confirm to Emily that Jacob was involved. And we know who else: Chad, an older boy, who lives in the Sixties flats that interrupt the Victorian terrace whose gardens back on to ours, and Henry, who's in one of the big houses next to them.

We barely know Wes, but we've seen him tending his garden, hoeing, planting.

"Obviously, we must apologise," we tell Emily. "But how can we make it up to him?" An apology is clearly required and we decide to offer a bottle of rum.

We tell Jacob that this week's 50p pocket money will be spent at Oddbins. Also that - and this is the bit he hates - he will go round with his father and say sorry all by himself.

And the other boys? "We'll tell the parents," I say. "Then it's for them to deal with it as they want." We know Chad's mum, Lynne, because her younger child is in Jacob's class. She seems very nice and her boys are happy, well-brought up kids. We don't know Henry, who goes to school elsewhere.

Lynne takes the whole thing very seriously. Chad, aged 14, immediately admits guilt and Lynne says that, being the eldest by far, he should take responsibility. He confirms the other perpetrators' names. We agree each to apologise, separately.

But that still leaves Henry, whose father is civil but non-committal. Jonathan apologises for being the bearer of bad tidings, tries to stress Wes's plight without heaping blame. "Thanks," Henry's father says. "We'll look into it."

Jonathan and Jacob walk up to the high street and come back with a bottle of Cockspur Fine Rum. They discover Wes is out. Jacob races home, temporarily reprieved.

"We'll try again later," says Jonathan.

It's a hot, hot weekend. The following morning, Sunday, Jacob goes off to play and ends up in Henry's garden. I set off to collect him, thinking this will be a good opportunity to meet his mum.

On the way, in the shimmering heat, I run into Lynne and Chad - both dressed up, Chad's hair freshly washed and slicked back - walking purposefully round to Wes's to make their apology.

"I'm afraid it was all my fault," says Chad straight away. "Well, you're doing the right thing, apologising," I say, impressed by his genuinely contrite air.

"He has no choice," says Lynne.

I get to Henry's street and knock on the big, yellow door. No reply. I try the side-door into the garden. Shrieks from the paddling pool, well- tended perennials, floral dresses and linen shorts with turn-ups, aroma of barbecue.

"May I help you?" asks an unsmiling, pink-faced woman who has to be Henry's mum. She's holding a tray of drinks. I see her clocking my cut-offs and unironed T-shirt. I introduce myself. "Sorry", I say, "to butt in, but I wondered whether Jacob was here?"

She says he's already on his way back through the gardens. I have purposely not mentioned the Incident, but she comes right out with it. "I gather there was some trouble in Wes's garden?"

"Well ... " I begin.

"I just want you to know: Henry was with me that afternoon, the whole time. So he couldn't have been involved - OK?" Steely, chillingly sure of herself, she continues: "I gather the kids from the council place were there?"

"Yes ... " I begin again.

"The trouble with those sort of people," she interrupts, "is they've got no garden of their own, so they've no idea how to behave in other people's gardens. Nice to meet you, anyway."

She nods and moves off with the drinks. I exit, pursued by the bear of her certainty.

Back at home, we drag Jacob round to Wes's for a second go at apology. Wes is home. Jacob looks him in the eye more or less - and apologises. Wes laughs generously, and won't take the rum.

"Just to say we're sorry," Jonathan urges. But Wes is adamant, says everything's OK, it's fine.

Now that the ice is broken, Wes says hello to us in the street at every opportunity. Jacob has learnt one of life's lessons and won't be Peter- Rabbiting through anyone's garden - for a while at least. As for Henry, we next see him in our garden,idly snapping branches off the buddleia.