When I was a young kid in junior school, perhaps seven or eight years old, one day this lad called Colin Bradshaw comes up to me in the playground.

'What time is it, Noony?' he asks.

'I don't know,' I reply.

'You mean you haven't got a wristwatch?'

'No.'

'I've got one. It's a special watch, like spies use. It's invisible.'

Now this Colin Bradshaw was the toughest kid in the class, and he was always hanging around with his gang, and playing tricks on the other kids.

'Wow! Invisible!' says I. 'Can I see it?'

'It's invisible, stupid! Anyway, I haven't got it on me today. It's at home. You can have it if you want. We can do swaps.'

So we made this deal, that Colin would bring the invisible watch in the next day, and I would bring my model of the James Bond Aston Martin DB5 (complete with ejector seat and guns that came out of the front and everything). This was back in the Sixties, and the James Bond car was easily the best toy of the time, everybody wanted one. Especially Colin Bradshaw.

'OK,' he says the next day. 'Give us the car then.'

So I gave him the car.

'Right. Hold your hand out. Palm up, stupid.'

I hold my hand out, and he puts his hand into his pocket and pulls it back out, holding the invisible watch. And he places the watch, gently, in my trembling palm.

And I believed…

In the first shop they bought a packet of dogseed, because Doreen had always wanted to grow her own dog. In the second, a pair of bird shoes, which fluttered slightly as Matthew put them on. In the third shop, Little Tommy bought half a dozen singing biscuits, five of which he swallowed straight away, because shopping made him hungry.

There were only nine shops in the entire city. In fact, the shops were the city, so vast they were and all encompassing. It was difficult to know where one shop ended and the next began. No wonder the children were tired already.

In the fourth shop Doreen chose a box of shadows, some of which she used to mask the pain in the head that Tommy's constant singing gave her. In the fifth shop, Matthew floated over the umbrella-pig cage in his bird shoes, claiming that if Doreen had bought the shadows, then he should have at least a single pig to keep the rain off. Doreen reminded him it never rained inside the shops, and that he should instead buy an egg of words. Matthew was becoming angry at the way this shopping trip was going.

The three young shoppers were determined to buy a single product from each of the nine stores. These precious items were to be the children's gift to their mother, for her birthday. Their mother, you see, had never once ventured outside the first shop.

In shop six, Tommy bought a penny ghost. In shop seven, Doreen purchased a Girl-of-Eternal-Flame Doll. In shop number eight, Matthew wanted to buy a genuine piece of cow, but Doreen told him they could no longer afford it. Instead, he was forced to buy a mansion house in London. In the ninth and final shop, Little Tommy bought a smoke-map of Manchester, which they used to retrace their steps through the aisles of the city.

On the way home, however, the dogseeds slipped from Doreen's fingers, caught on a slight breeze. The bird shoes tried to catch the seeds, only to crash into a display stand, tumbling poor Matthew to the ground. He landed on Tommy, who swallowed his last song biscuit accidentally. Doreen used many more of her shadows to wipe away Tommy's wailing. Matthew's egg hatched prematurely in his pocket. The resulting cloud of words gathered over the Flame Doll, forming the word 'locust' in the air. The doll ran screaming into the mansion house, shooting electric sparks from her hair. The house burned so fiercely that not even the fire brigade could put it out. They'd forgotten to bring their hosepipes.

Tommy smoked his map completely to get them home to Mother's little kiosk. All that remained was the penny ghost and a single shadow. The children were in tears by then, but their mother accepted gratefully the gift of the shadow and told Little Tommy he could keep the ghost for his trouble and kindness. That night he played with the spirit, as his mother wiped her sad eyes with the birthday shadow and told them the story of the mythical tenth shop, the one that lay beyond all the others.

Remember Spook?

—No.

Sure you do, came out when you, me and the rest of the world were just a bunch of kids. It was a bit of a craze for a few years, a new soft drink product. Ninety-nine per cent sugar; one of those things that tastes disgusting first off, but you can't help getting hooked if you persist with it. It was called Spook, I guess, because it was like clear liquid to start with, no flavour, with this neat gimmick in the cap. You could twist the cap six different ways to get six different flavours. Nothing special looking back, just some cheap chemicals released according to which flavour you chose, but the sort of thing that kids go mad for.

—Oh, right. Orange, strawberry… apple…

That's it. Lemon, cola or elderberry. Anyway, remember Nesbit?

—Who?

Come on, that scrawny little brainbox with the rich parents? He was the one who first introduced us to drinking Spook, because it wasn't advertised or anything, you just had to know it was there somehow. Whenever we went to the shop, it was always, 'I'll have a Spook'. That's all he ever asked for, especially after he'd discovered that turning the cap in a certain clever way, you could get to mix the flavours. I'm not sure if the manufacturers even knew you could do that, and we had to pay Nessie to do the combinations for us, because only he knew the secret.

—Nessie?

Nesbit. Now you've got him. He got us all hooked on the stuff for a while, trying out different combinations. It was neat, the way the two colours merged to form the new flavour. He was good at maths, I remember, and he'd worked out with six starting flavours you could have more than sixty different flavour combos, if you could only discover the correct ways of turning the bottle top. I can't remember the exact figure.

—He made up names for them?

That's right. Orange and cola he called orancola. Strawberry and elderberry he called elstrawb, and so on. He'd found out all the ways to combine two of the flavours. Then he started on mixing three of them. It was tricky stuff, getting the cap to twist just so to release three at the same time. He'd spend hours with the bottles - playtime, after school, whenever. I went round to his house one time, he was sat on his bed with dozens of bottles all around him, twisting at one like he was in a daze, like it was the best puzzle ever.