Hammages Department Store started preparing for Christmas on the previous Boxing Day, and it showed.

The ground floor was split between perfumes and makeup, jewellery and the food halls, which made it a great, glittering place, full of glass and coloured liquids and sparkling gems, pungent with a seasonal spicy sweetness.

Everywhere there were trees and baubles, mechanical angels and piped carols and in between them strange foods and stuffed animals, cases of ticking watches and great, sheer cliffs of pink perfume bottles.

And people. Hundreds of people, all pushing and shoving, barely paying any attention to the great chiming, musical Christmas that had been erected for them, all concentrating on only one thing: getting their presents in time.

“Right, you two, hold on to my coat and don’t wander off. Books first, I think.”

And Oscar’s mother strode off towards the lifts, with them all following after.

They caught the lift doors just as they were closing and all squeezed inside. The lift was packed full of shoppers and Oscar was jammed up against the lift attendant, who pressed the buttons and announced the floors.

“Floor Two, Ladies’ wear and shoes.”

Oscar squinted up at the buttons the attendant was pushing. There were two columns of them - the ones at the top were numbered: 1, 2, 3, 4, 5, 6… And then… nothing - the rest were strange colours - things the attendant pressed to stop the lift and open the doors.

“Floor Three: Men’s wear, Children’s wear, Sports wear and equipment.”

There was no Floor Seven! Oscar daren’t take the piece of yellow paper out of his pocket but he was sure it had said Floor Seven. But there wasn’t a Floor Seven; at least there wasn’t one that the lift went to. What did it mean?

“Floor Four: Books, Toys, Christmas Department, Pets, Antiques and Father Christmas.”

“Quickly, boys, out, out! Oscar, please pay attention, we’re getting out here.”

And with his mother’s hand placed firmly between his shoulder blades, Oscar found himself propelled out into the Books department.

“Right, you two, I have to look for some things, so stay in the department where I can see you. The children’s books are here - I’ll be over there.”

But Oscar was too confused - there was only one book he was interested in right now and he already had that one tucked safely away in his backpack.

He stood in the aisles of the children’s books, watching his brother cheerfully dismantling an elaborate display of picture books, wondering what to do.

And that was when he saw it: a nondescript door tucked away by a bookshelf, marked: ‘Stairs to all Floors’.

All floors? Surely that had to mean Floor Seven as well as all the others. He looked around - his brother was absorbed, his parents were futilely searching for books for people impossible to buy for: this was his chance.

With only a moment’s hesitation Oscar then did the second wrong thing of our story and without saying a word, left his family and set out to explore the ’stairs to all floors’.

His brother, who was busy methodically breaking all the pop up books in the shop, didn’t even notice he had gone.

The stairs were plain and lonely and smelt of disinfectant. Oscar started up straight away.

One, two flights and there it was: Floor Five: Antiques, Home Furnishings, Gardening and Haberdashery.

Two more flights and he was as high as the lifts went - Floor Six: Audio Visual, Gadgets, Musical Instruments, Gifts.

And there it was: another flight of stairs, dimly lit, leading upwards into darkness, up towards… “Staff Only”

That’s what it said: “Staff Only”, a sign hanging on a chain that stretched across the stairs, cutting them off from the rest of the store.

Oscar stared at the notice, forlornly, not sure what to do, when he realised that he could hear voices approaching from above.

He crossed over to the door leading to Floor Six and half stepped through it, ready to look as if he was going somewhere instead of just loitering. He knew that adults tended not to like to see children just hanging around with nothing to do - it reminded them that they never got to hang around aimlessly themselves any more and that made them angry.

The voices came closer. It was two shop assistants coming down the stairs from above. One of them unclipped the chain and then secured it again after they had passed through.

“Have you ever peeked through the door?” one of them said.

“Oh no, well, I wouldn’t want to - the people you see on the stairs. I dread to think what goes on in there.”

“Oh, I know what you mean… still; it makes you wonder, don’t it?”

“Well, you wonder about that and I’ll wonder about Darren from white goods…”

And they passed out of earshot down the stairs.

Oscar came out of his hiding place and crossed to the stairs. He unhooked the chain as he had seen the shop assistant do and looked up the stairs to where they turned out of sight, into darkness.

They must have been talking about Floor Seven, those shop assistants, surely… the odd people, the secret place: they must have been. It had to exist… it had to…

And, if it did: what an extraordinary adventure! He stepped up onto the first step. Nothing happened. The stairs were silent and empty. He hooked the chain back up behind him and climbed on up, into shadow.

One flight and the stairs turned, just like the floors below. There was no light ahead and the steps were getting darker and darker.

One more flight, each step taking him deeper and deeper into shadow. Surely he was there now… surely this must be Floor Seven…

Somewhere up, up further flights of stairs, there was a window, and light, but here all was dim and obscure. Were there doors there, to the left? Was that a number ‘7′ on the wall? He couldn’t quite make it out.

He pushed against what might be a door and it opened into a deeper, solid darkness. Oscar hesitated. He didn’t particularly like the dark. He particularly didn’t like being on his own in the dark. He very definitely didn’t like being on his own in the dark when he wasn’t entirely positive that he was on his own. And he was becoming pretty sure that he didn’t like being on his own in the dark on a secret floor of a mysterious store where there were odd people on the stairs and somewhere, possibly, magic.

It was that thought that did it. What if it really was there - the Magical Supplies Department, just beyond this darkness? What if it were there but because of this little twinge of fear, he missed out on it altogether? What was worse? The darkness or missing the adventure?

Oscar decided that he knew the answer to that and stepped forward, letting the door shut behind him.

This story happened because two people made mistakes and did things that they shouldn’t have. One of the people made more mistakes than the other, but neither of them made them very often. One of them did the wrong thing deliberately; the other one was just absent minded. He should have been paying attention, but then he was very busy.

But without these mistakes being made, the story wouldn’t have happened, so perhaps they weren’t mistakes after all.

The first mistake happened around the start of October, around Oscar’s birthday.

Like a lot of children, Oscar usually made a long list of presents that he wanted for his birthday and I’m afraid to say that he quite often got what he wanted, too.

But one person who almost always managed to surprise him was his godfather, his Uncle Rufus.

Uncle Rufus wasn’t around very much, he was often travelling or busy on what he claimed was important business, but at least his presents were usually something odd or interesting.

One year it had been a large round stone that he had claimed was a dragon’s egg, and another time it had been a bottle of dark green glass with what looked like a wisp of smoke in it. The bottle had had a yellowing label on it reading ‘One Genuine Ghost’ which everyone had agreed was nonsense, although no one had had a good explanation for what the smoke might be instead.

Uncle Rufus’ presents were also always a surprise because you never knew when to expect them. Certainly not around your birthday. Once one of them had been early, but often they were late. Some actually  arrived in the wrong year, some were so late as to be actually almost early again and sometimes he didn’t even send a present at all, which was, perhaps, just a little too surprising.

So Oscar found himself torn between looking forward to his surprise and then not wanting to look forward too much in case it was really late, or never actually came at all. Unfortunately all the feverish anticipation only made the present even more of a disappointment when it finally did show up.

It was only a week late this time and was there waiting for Oscar when he came down for breakfast. A solid rectangular package wrapped up in brown paper. Oscar could tell it was from Uncle Rufus because it had his address on the back.

They were already running late and Oscar knew that the sensible thing to do would be to save the parcel until he got home from school, when he could really savour the delight of unwrapping and concentrate on his present properly. It is hard, however, to be sensible in the presence of a surprise and Oscar opened it immediately.

It was a book. It was a hardback book with a rather unpleasant pattern of greens and purples all over it. And drawings. Spidery little drawings of scientific equipment and mathematical symbols. What was it? He turned it over. “Kennedy’s Alchemical and Thaumaturgical Primer, 9th Edition”. What did it mean? It didn’t sound very exciting. It sounded, in fact, like schoolwork.

Oscar’s mother shouted from the front door.

He opened the book and looked at the front page. “Kennedy’s Alchemical and Thaumaturgical Primer, 9th Edition, by A. J. L. Kennedy, BA (Oxon), FROM, A textbook and educational guide containing exercises, experiments and resources…”

“Textbook”? “Textbook”!?

It was schoolwork! Why on Earth had Uncle Rufus sent him a textbook? Had he been talking to his mother?

He flicked through the book. There were long, dull looking paragraphs… lists that looked like they might be tests… diagrams of some kind of experiment… this was ridiculous! It really was a textbook.

His mother called again and this time, apparently, she really meant it.

Oscar threw the book down in disgust. A textbook! If he was going to have to write a thank you note, it wasn’t going to be a nice one.

Oscar liked to think that the house was full of friendly ghosts that moved things around when no one was looking, but he suspected that it was actually his mother. He was used to things tidying themselves up and didn’t notice the textbook arriving on the shelves in his bedroom.

But somehow it made it because it was definitely there one rainy morning two months later when he was bored and had nothing to do.

He ought not to be bored, of course, someone was bound to be able to think of something for him to do, but he was being very careful not to ask anyone. He was enjoying being bored, in fact: his birthday had long gone and it still wasn’t Christmas. He was tired of all his toys, it was a Sunday morning and it was raining. It was a good time to be upstairs on your own with nothing to do.

He wandered listlessly around his room, picking things up, finding they weren’t fun at all and putting them back down again.

He picked up a book and started leafing through it, barely noticing what it actually contained. It didn’t look very interesting apart from that picture of a dragon. That was a good dragon. And that wizard. The wizard was standing in the middle of a circle he had drawn on the floor while smoke swirled around him, and in the smoke, horrible, leering faces appeared.

Oscar started looking at the book more closely.

“A spell for the conjuration of spirits” started one page. A spell? “An experiment for the creation of a golem” said another. “The Foundation of the Royal Order of the Magi”, “On the sorcelation and entrapment of spirits”, “Appropriate robes and vestments”. What was this book?

He turned to the front page.

“Kennedy’s Alchemical and Thaumaturgical Primer.”

It was the book from Uncle Rufus!

It was a textbook, but it was a textbook about magic!

Oscar felt at once excited and a little guilty. This was the most amazing book he had ever seen and he had almost missed it because it was a textbook and he hadn’t bothered to look at it closely enough.

Well, he was looking at it now. He closed the book and carefully arranged the cushions on his bed into his favourite reading position. Then he squirmed down into them until he was perfectly comfortable. Finally he picked up the book, opened the first page, and…

“Oscar, come on, we’re going!”

It was his mother shouting from downstairs. Going? Going where? He couldn’t go anywhere: he had to read this book. He went to the door, still clutching the book.

“Mum, I’ve got stuff to do.”

“Yes, you have: you’ve got to come downstairs, put on your coat and get into the car.”

“But Mum, I’m busy… it’s… its schoolwork…”

“You can do it later…”

“But…”

“Oscar, I told you this morning, when you weren’t listening, we’re going to Hammages to see Father Christmas: you’ve been going on about this for weeks so get down here, now.”

Of course: she had told him, he had just forgotten it in his excitement. There was no way he could get out of this: everyone was going and they’d never leave him on his own. Anyway, he didn’t want to get out of this - he really had been looking forward to it. The visit to Hammages department store was their Christmas tradition. They all went every year and Oscar and his brother went to see Father Christmas and his parents would buy them each one small toy as a treat. In fact, now that he stopped to think, he was still looking forward to it.

Also Oscar had the sneaking suspicion that his mother might not wholly approve of a book that had real spells and genuine experiments in it. She might insist on reading it first, or doing them with him - or worse, take the book away altogether. He had to be careful about letting on how excited he was.

“I’ve got to put my shoes on.”

“Then hurry up, please.”

He turned to find his shoes. There on the bed was a slip of yellow paper. It must have fallen out of the book when he sat down to read. It was blank on one side, but on the other side it said, in heavy, black letters:

“20% student discount on all alchemical and thaumaturgic supplies with this voucher. Hammage’s Magical Supplies Dept, 7th Floor.”

“Hang on,” shouted Oscar, “I’m coming as fast as I can.”

It was a cold and misty December night and Big Ben was chiming thirteen.

A man standing on Westminster Bridge was trying to set his watch to the right time and at the thirteenth strike he looked up angrily at the bell tower.

At this the hands of the clock face curled up like a pair of sinister moustaches and the two and the ten narrowed meanly, and the whole tower bent down to glare at the man on the bridge.

The man stood for a moment, paralysed with fear, as the tower loomed down over him, menacingly. Finally he dropped his head and saw that all the numbers on his watch had budged round and a new 13 had appeared at the top.

The man set his watch to thirteen o’clock and, head still bent, hurried away across the bridge.

The clock straightened up and then, just for laughs, struck half past thirteen.

And all across London, above the dark and glistening roofs, all the other clock towers and belfries replied, each one striking a completely different time.