Contrary to what you might think, the Black Market isn't centred in London. Seems strange, what with the capital being the living, beating heart of the whole country; it's the centre for everything. News, music, art: sackfuls of culture churned out every second in an incestuous squall of creation and distribution. That's the problem, really.

The Black Market isn't based in London because too many other things are. Including the other black market. The one that peddles drugs and sex and ruined lives. Sure, our Black Market thrives on the same things, but it's a better class of ruination. If your chosen method of degeneration had to be obtained by way of a hazardous journey into another dimension, wrestled from the jaws of an unspeakably monstrous beast, and then brought back in a jar sealed with a maiden's kiss in moonlight –then you know it's quality stuff. And a lot more exciting than a bit of white powder.

Of course, the maiden's kiss or suchlike is often replaced with duct tape. Duct tape can do anything.

The point I'm trying to make is that the Black Market is everywhere. It's more of an idea than a place, you see. You are just as likely to find a dealer in the heart of Camden Town as you are in a sleepy Lincolnshire village. The Welsh contingent is particularly thriving. Lots of residual magic in Wales. Something to do with the sheep.

On a mild but drizzly day in March, the Black Market was thriving more specifically in a Cumbrian town called Cockermouth. I may or may not have decided to take up residence in this location purely for its delightful name. I am a child at heart.

I was in this part of the country – the northerly, constantly raining part – as a result of some business dealings with an associate of mine: the affable witch Mark Demdike who I rely on for a supply of ready-mades pells and potions. After an incident with a troll (in which I heroically and entirely selflessly saved the day) I find myself both thankful to still be alive, and consequently fully stocked.

"'m hungry, gwas."

And then, of course, there was Ang. Two and a half feet tall with pointy ears sticking out from under a flat cap, the little Welsh coblyn had been my travelling companion for a few weeks now. She didn't take up much space, but her debris sure did. Pie wrappers, beer bottles and spent tea bags – if it wasn't covered in pastry she wouldn't eat it, and if it wasn't ale or tea she wouldn't drink it. It may not sound like much, but when the entirety of your living area consists of one Ford Escort estate car, space fills up fast. And she snored like a wildebeest.

"We'll get food later, Ang. We need to make some money, first." I pulled out some fresh potion bottles and heaped them in Ang's skinny arms. "Arrange these on the table, would you? Neatly."

"I ain't doin' your work."

"'My work' is how we fund all those pies you eat. If you want to keep eating, it's going to become 'your work' too."

"Fine talk. We been out here all mornin' an' made no sells. Ain't no-one here's gunna buy your heathen magickry and cheap doo-dads."

"Just be patient."

"This's a farmer's market, twpsyn. People are here t'buy meat 'n' cheese, not charms 'n' potions."

"Trust me, Ang. There's always a customer out there. You just need to learn to spot them."

"There ain't none here."

I met her sceptical gaze. Time, I decided, to give Ang some instruction in the art of Black Marketeering.

"Settle in, Ang. You're going to learn a bit about our consumer base."

"Our what?"

There are two broad strains of customer that I'm always on the look out for. The first type is the hippie, who comes in several flavours. The most common flavour is the young, earth-loving waif who, despite a strong abhorrence of the ecological impact of commercialism, is nevertheless able to stomach spending a great deal of money on outlandish jewellery and stylish tie-dye outfits made by children in Thailand (but in an environmentally friendly manner).

These ones are suckers for cheap and colourful jewellery, especially if you can claim it was made using 'traditional' craft skills in a poorer country (funny how no one considers 'traditional' to encompass slave labour).

Another type of hippie is the older, not necessarily wiser New Age Wicca enthusiast; the ones who loudly proclaim the healing power of crystals and mud, and whose spells contain not a single ounce of blood or newt's eyeball. (Actually, crystals can be pretty magical in the right circumstances – but you have to do more than just pile a bunch of rocks on your body and hope.)

Crystals and other shiny things sell well to these guys in any weather, but you have to know your geology. When I first started this gig I quickly learned that 'this pink rock' and 'that greeny-blue rock' was not a satisfactory method of identification for even the most disinterested of tourists.

Every so often you'll encounter a New Age hippie who actually has an understanding of real witchcraft, and these ones can be quite profitable – if overly sanctimonious. I receive no end of lectures about how one should not try to control the will of others through spells and potions. What are spells and potions for then, I wonder?

It's the love potions that attract the most ire: "You can't just make people fall in love!"; "You can't force someone to do things against their will!"; "It's unethical to affect the fate of others!"

"'tis 'nethical," observed Ang.

"Well, yes. But do you have any idea how much these things sell for?"

Besides, I explained, the naysayers are technically correct. You can't force someone to fall in love with you. At least, not with what I'm peddling. These concoctions are less love and more lust, like a really strong aphrodisiac: Viagra for the mind. So it's not going to turn the object of your affections into your soul mate overnight, but it might be enough for a one-night stand. Except, you probably won't even get as far as the one-night stand because, as the naysayers attested, it's bloody hard to force someone to do something they don't want. Actively controlling a person takes a lot of willpower of your own, and it's rare for there to be a ready-made short-cut available.

But I'm not going to tell my customers that. Why should I? It says it all right there on the bottle. Just in very, very small writing.

Now if, on the other hand, you want to do something to a person, that's much easier, and short-cuts abound. And because humans are vindictive creatures at heart, revenge potions are among my best sellers. These brews come in tiny vials of exquisite, one-use satisfaction. I stock the classics: tonics that cause warts and boils, minor accidents, money troubles, that sort of thing.

There are also plenty of more interesting alternatives; Mark's a dab hand at inventing increasingly creative ways to make a stranger's life miserable. My favourite from his last batch was a tonic which effects a person's perception of their own genitalia. Lasts for a week, thoroughly freaks out the recipient and puzzles any doctor they go to, who of course can't see anything out of the ordinary. (Results vary: it may appear larger, smaller, or have turned purple with sparkles. I once received the gleeful report that my patron's ex-boyfriend had become convinced it was singing to him. Had a voice like James Brown, apparently).

Of course, these products also invite plenty of criticism from those with a loud conscience – but I simply can't hear them over the sound of how much money I'm making.

"An' how much money is that, gwas? Cuz I heard we can't even afford pies no more." Ang leered at me over a box of voodoo dolls.

"We've just hit a slow patch. But rest assured there is never any shortage of spurned lovers or disgruntled employees. Even Cumbria is rich in those."

It is these spurned lovers and disgruntled employees that make up the second strain of customer I'm on the lookout for. These are the individuals who really mean business, they have an axe to grind and I'm here to provide the grindstone. Unlike the hippies – who may be identified by their colourful costume, vaguely occult jewellery and flowers in their hair – this demographic wears no such uniform.

Instead, search for the sullen expression, the white tan line on the ring-finger. Listen for the conversation, the frustrated tone of voice and curl to the lip.

I nodded at a bloke with hunched shoulders opposite us. He was staring moodily at a selection of cabbages, brow furrowed as if trying to read a sign in a foreign language.

"See him? Creased up clothes, no ring, keeps scowling at pretty women? Screams 'divorce papers', don't you think?"

"Right. Or mebbe his wife sent 'im to get cabbages because he broke the iron an' dropped his ring down the privy."

"Aha," I said proudly. "I know he's divorced, because he was just telling the cabbage-seller all about it a moment ago."

"That ain't no skill. An' it ain't right to listen in."

"It's critical market observation."

"Ye just like spyin' on folk."

She dumped another box haphazardly on the table. Its stacked contents – a fine array of Holy Grails, totally legitimate for a given definition of the word 'holy' (i.e. with holes in) – toppled and crushed the display of enchanted (cursed) roses I had been working on.

"You better tidy that up," I said. "Or there'll definitely be no –watch the thorns –no pies later."

"Won't ever be no pies, if ye only sell to the desperate."

I bristled. "I'm a salesman, Ang. I can sell to anyone."

"Aye? What about them?"

She indicated a gaggle of girls coming our way. Late teens or early twenties, not a natural-blond among them.

I squared my shoulders. "Watch and learn."

I picked up my tray of jewellery and thrust it forwards as they passed.

"Fine jewellery for fine ladies?" I said grandly. I whipped out a cheeky smile too.

They exchanged glances, then peered down petite noses at the tray.

"Mood rings?That's so nineties!" exclaimed one of them. She held aloft a pink ring."Wasn't it, like, they'd be red if you're angry, blue if you're calm? Or green? I think mine were always green."

"Don't they like, change with heat, or something?" said another.

"No miss, not these ones," I interjected. "These rings change your mood, not the other way round." I held forth a sample of rings in the palm of my hand and selected them one at a time. "The pink ones, like this, they encourage your feelings of love to surface. Red ones bring out feelings of stress and anxiety – a good gift for whoever's been irritating you lately. Green ones–"

"Oh, look at this cute necklace!"

"Let me see. Oh, isn't that the star of David?"

"No, it's a pentangle."

"–inspire patience," I finished, wryly. "It's called a pentacle, miss."

"Don't witches wear these?"

"Yes," I said. "But so do lots of people. You see, it's a protective charm and–"

"Get it for Emma, she likes that spooky stuff."

"Nah, it looks kinda cheap."

Under the table, I heard Ang snort with derisive laughter. I changed gear.

"How about this pendant?" I proffered a silver wedjat amulet: the archetypal Egyptian eye motif. "Sterling silver, comes with a delicate silver chain too."

"Ooh, that is nice. Isn't that nice?"

"Yeah, definitely. Do you have any ankhs? Like, ankh earrings?"

"Ankh pendants, yes," I replied.

"But, like, earrings?"

"I'm afraid not. Perhaps instead I can interest you in–"

"Oh, hey! Look at this cute little rabbit foot!"

"Ew, get it away!"

"That's disgusting."

"I think it's cute. Don't you?"

"Uh, no. I'm vegan." This one rounded on me. "Did you kill this rabbit?"

I kept my smile. "No, miss. Wouldn't harm a living thing."

"Well, you practically did kill it, because you're selling it. Fur is murder!"

She threw the rabbit foot on the ground.

It bounced.

She picked it up and inspected it quizzically. "It's made of rubber."

"What?" said her friend.

"The fur's just stuck on. Look."

"You mean it isn't real?"

The group fixed accusative glares at me.

"Animal-friendly?" I tried.

They left without buying anything. I despair.

"That was sellsmanship, was it?"

"Shut up, Ang."

One of the girls hung back, still idly pouring over my wares. I had mistaken her for being part of the group, but evidently she was on her own. Had a more down-to-earth air about her, actually. More patience in the eyes and thoughtful creases around the mouth. She was perusing the potions, discreetly arranged to the back of the table.

"Cleansing room spray?" she inquired, pointing to the label of one.

"Clears out any negative energy, miss. Fills the air with harmonious vibrations and positive energies," I said, adopting an easy smile. That's one of my own creations. Plastic spray bottle filled with water, salt, and whatever perfume I can get my hands on. A few floating flower petals give it a nice aesthetic quality (pro tip: fancy petals are easily obtained all year round from supermarket flowers – security isn't looking out for a man surreptitiously filling his pockets with plucked petals).

She set it down, disinterested, and picked up another, turning the angular glass bottle around in her hands.

"Careful with that, miss. Pretty strong mixture, that one."

Her thumb brushed over the label, and one delicate eyebrow rose as she read aloud: "Hopping Mad Medley. Convert the recipient's inner rage into an uncontrollable desire to hop?"

"Fun, harmless come-uppance for that person in your life with a bad temper. Satisfaction guaranteed." I grinned broadly.

She returned my smile and picked up another bottle. "What if I wanted something less... harmless?" she said, eyes trained on the vial in her hand, as if she wasn't really interested in the question she was asking. Aha, this one's a believer, sure enough.

"Might I suggest our Odious Miasma, for a stench that just won't leave? Or perhaps the Hapless Harry, for a bout of bad luck. But if you want to hit 'em where it really hurts, I'd recommend Beggar's Fortune, for a spell of money troubles."

"Mmm."

She appeared deep in thought, though it didn't seem like she was trying to decide on a manner of vengeance. There's usually a spark in the eyes, a little rush of excitement as they contemplate revenge. But she stared at my wares as if she was merely comparing vegetables.

"Perhaps you were looking for something else?" I tried.

"Have you got anything else? Something... interesting?" she said, gaze still distracted, aimed at the table.

I rummaged through my stock. "Something like... a box of infinite compartments?"

"Dull."

"Sacrificial earspoon?"

"Common."

"Aztec idol?"

"Last year." She turned away and made to leave. "I'm sorry to waste your time. I thought you might have something special."

In a split-second I weighed the situation, and found it to be a good one. From the depths of my trench coat I retrieved a tin box. "Well miss, if you wanted special then you should have said! I can assure you, you have come to right place. I just so happen to have this very rare, very beautiful commodity all the way from the depths of Wales. Have you ever heard of a 'bluecap'?"

She looked at me properly for the first time. Now there was a spark in her eyes.

"No," she said. "What are they?"

I grinned again and tantalisingly ran my fingers along the edge of the box. "They are mining spirits, and they seek out treasure. One of these beauties will lead you to riches beyond your wildest dreams... Take a look."

I pulled away the lid, and a soft blue glow illuminated the woman's entranced features.

"Oh, how pretty..."

Without warning, Ang reached up from under the table and slammed the lid closed. "Not for sale," she said, sternly.

"Excuse me," I said, smiling brightly to my almost-customer. "Let me just talk to my associate here."

I ducked down to Ang's level. "What are you doing? We had a deal, Ang. Bluecaps for travel, and my generous assistance. They are mine to sell now."

"To a good home, pentwp. Them's the terms."

"And just what is a 'good home', huh? What does it matter to the bluecaps, anyway? They're dead! Spirits! They don't care!"

"Bluecaps need to work, gwas," Ang growled. "Not to be sittin' on a shelf for some stuck-up, soft-handed ast to gaze at of an eve."

I grit my teeth and forced myself to speak calmly. "All right, Ang. How about I ask her how she's going to look after them? I could even give her a set of care instructions if you like. 'Walk your bluecap at least once a day,' sort of thing, all right?"

"No deal, gwas. Don't like 'er."

"For fu– heaven's sake. Tough. We already made our deal, Ang. I'm holding up my end of it."

"Oh? Found a lead on me missing kin, did ye?" She leered at me until I looked away.

I rose, forcing my features to relax and regain their friendly composure.

"Sorry about that. Now–" I closed my mouth, puzzled. The woman had disappeared. I exhaled my exasperation, and thumped my fist on the table. "Christ, Ang. Look what you've done. Scared her off."

"Good."

I wanted to throttle the snotty little creature. That sale could have made the day.

I reached down to retrieve the bluecaps, but my hand grasped thin air. I looked down in slowly dawning horror.

"Oh, shit," I groaned.

"What?"said Ang, suspiciously. She peered out from her hiding spot. From the look on her face, I gather my expression must have said it all. "You best not've lost them bluecaps, gwas," she said, icily. Her normally pale features were slowly gaining colour.

"I can't believe she– I mean, she seemed quite nice." I desperately scanned the crowd, but I knew she'd be long gone. "What a, a–"

"Ast."

"What?"

"Bitch."

"Yeah. Exactly that."

"It's your fault," hissed Ang. Her ears might as well be steaming, she had turned so red. "Twpsyn. You utter twpsyn."

"If you hadn't distracted me–"

"Then she'd've still made off with 'em! Right under your nose! Ffwl!"

"Stop shouting, Ang. We'll get them back. I'll find a way."

"How?"

That was a very good question.