I was in my 20s when I got a job working behind bars, a writer in a men’s prison, with the loose remit of fostering creativity. On my first morning I hitched a stiff leather belt around my jeans and was issued my own set of keys. The biggest, draconian looking, was for entry into the prison itself, accompanied by a cluster of smaller keys for the library and my tiny office. As I walked across the prison yard the chain jingled. I felt absurd, like a cat with a bell.

Training for the job had felt shockingly short. A single blurred week of briefings with my fellow writers, each of us having been assigned our own prison. Dress code (comfortable but non provocative), hostage situations (don’t fight back), manipulation and psychological grooming (don’t give away details of your personal life, never traffic any item, not even a Mother’s Day card, in or out of the facility for a prisoner). We were guided through the activities we’d be expected to instigate – plays, prison newspapers, writing workshops. I had zero experience of teaching. Not a natural disciplinarian, my voice when it rose above a certain level grew reedy and thin. How did I expect to hold the attention of a classroom of prisoners? What if a fight broke out?

As it turned out, my students never gave me much hassle. This was a resettlement prison offering sought-after training in construction, and a painting and decorating course. Prisoners often requested a transfer specifically so they could pick up a trade. For the most part, the men I worked with were diligent when it came to writing assignments, eager to impress, attentive. My troubles came in an unforeseeable shape and size. An egg.

The egg was gold with a small, hinged lid and mounted on an inch-high plinth. It hadn’t been on my floor at the start of my day and then it was. The men loitering in the recreation area outside my office remained poker-faced, as if a Fabergé-style egg materialising out of thin air were a normal occurrence. I picked up the egg gently and put it on my desk, holding it in cupped palms. For a long time I sat staring at it. The bell rang for “tally”, one of several head counts that took place throughout the prison day. Prisoners put down their pool cues and dominoes and automatically began shuffling towards their cells. “Oy Miss, are you going to open it or what?”

There were a few reasons the egg was a problem. No doubt a custom-made present like this fell under the category of grooming I’d been warned about. I thought back to my training. Employees were not supposed to accept gifts of any kind. A few weeks previously an anonymous inmate had posted me a box of luxury beauty products. I had peered wistfully at the contents and then dutifully handed it over to security. Admin staff came in and cooed over the potions. Somehow I didn’t think my co-workers would be as eager for a hand-blown egg, even one with floral decoupage and gold beading. Regardless, I was obliged to report any out-of-the-ordinary behaviour.

The egg was made from contraband items, begged, borrowed and probably stolen. When I flipped open the gold lid, nestled inside was a perfectly proportioned rose, carved from what appeared to be, on closer inspection, a tiny chunk of raw potato. I held it up to my nose. A potato?

Food in prison is currency, part of an elaborate bartering system. Along the way I had learnt to hustle. During long weekend rehearsals, when it was almost impossible to get performers to arrive on time, I stocked up on Waitrose snacks. There were mutterings about McDonalds but the cast thanked me and pocketed the miniature pork pies. When attendance dropped in my writing classes I offered a food-reviewing workshop, laying out a rainbow of exotic fruits on a desk. My star pupil, a talented rapper, launched into a riff about physalis. When he was done he clicked his tongue: “I was a shelf stacker in Tesco.”

My office overlooked the communal area of one of the wings, next to a makeshift cafeteria where inmates queued to collect their meals, shuffling restlessly in a long line, brown trays tucked under their arms. The quality of food was notoriously poor (during an annual inspection well over half of the men had rated their daily meals as either bad or very bad). On return to their cells prisoners waggled items of food at me through their zippers; unidentifiable cuts of meat, flaccid sausages. They hurled bread rolls at one another as they walked back to their rooms.

In an attempt to resolve the problem a new kitchen opened shortly after I arrived. Food had improved, at least according to staff, though in truth I never saw an officer willingly ingest anything a prisoner had prepared.

A few days after the arrival of the egg, I visited the new kitchen facilities, curious about the source. Judy, the catering manager, issued me with a pair of paper shoe-covers and a medical-looking blue cap. We were friends of a sort. A relentlessly cheerful woman, she watched every event that I produced, plays and Christmas pantomimes, grinning in her kitchen whites, giving my performers two thumbs up.

Following Judy’s instructions an orderly upended a bag of frozen burgers, clattering the brown patties out onto an enormous oven tray. A radio played, someone whistled. A job in the kitchen was a coveted position. The atmosphere was jovial, relaxed even. It shocked me that there were prisoners, in for violent offences, chopping vegetables and handling blades. I had once spent a sickening, sweat-drenched hour searching for a missing stapler from my desk, a fireable offence I thought, picturing the entire prison on lockdown until the stolen weapon was recovered. Later I discovered it in a waste paper bin. Judy snorted when I told her this. Behind a lockable cabinet, knives were arranged in a row like a police line-up. Nobody, including staff, left the room until every blade had been returned. But it wouldn’t be unfeasible, I imagined, to smuggle out an egg or potato.

Frequently there were delays during roll call (a workshop tool gone astray or, on occasion, a prisoner), so that by the time the men were handed their meals, food was lukewarm. But it wasn’t only the prisoners I felt sorry for. There was no staff canteen, not even a communal area, as far as I could tell, for officers to sit and drink a cup of tea during a break. A few ate in their cars. Others haunted the empty “visits room” where a vending machine occasionally spat out free crisps. I ate huddled over my desk, embarrassed to be seen with my supermarket sandwich and a tub of fruit. Men on my wing habitually swooped past my door to catch a look at what I was up to. Whenever there was an open packet of biscuits on my desk numbers grew, like gulls following a trawler.

Eventually I noticed a band of four or five officers who passed my door at almost exactly the same time each day before they knocked on the library door. There, hidden from sight behind the stacks, they ate from Tupperware tubs and flicked through tabloids. One lunchtime, I let myself in after them, still fumbling with my keys. I took a seat next to a low-ranking female officer that I knew. No one said much to me. I regretted bringing in hummus. “You’re the writer lady,” an officer said without looking up from his newspaper. He pushed a packet across the table. “Better have a Hobnob.” The librarian made a round of tea. These became my people, the library crew. If there was a birthday we splurged on a jacket potato at the local garden centre, the nearest place to get a hot meal. A few times I almost asked their advice about the golden egg (by then locked in a filing cabinet in my office), but I changed my mind.

The egg turned out to be just the start. In the months that followed, a series of presents, frequently edible, began to show up in my office. A slice of banoffee pie, for example, was delivered to me by one of my regulars, a thank you for some advice I’d given about a parole letter. Not just handmade but cell-made. How on earth did you bake a pie in a prison cell? The chef grinned. “Easy, miss.” A few ingredients such as the condensed milk had been purchased from his weekly canteen – a selection of supplies and toiletries on which men are able to spend their minimal workshop wages. He persuaded another wingmate to order a pack of digestives, while an insider from the kitchen was willing to exchange some canned fish for a few bananas. Covert cooking, I began to realise, relied entirely on collaboration. I found this system of “food boating”, as the men called it, an unexpectedly comradely phenomenon in an institution whose entire purpose, surely, was to isolate. But I still didn’t understand how a handful of ingredients could be turned into a pie that looked and tasted almost as good as one you’d find on the other side of the fence. The prisoner tapped his nose, reluctant to divulge a trade secret, before ego got the better of him. First, he explained, he had stripped the insulating cable on his hi-fi, using the exposed wire to “defibrillate” a can floating in a tub of water, instantly transforming condensed milk into dulce de leche. Pour the caramel over some crushed biscuits and top with mashed banana and you had banoffee pie.

I was stunned by the ingenuity. The next day the same man dragged a reluctant fellow prisoner into my office, ordering him to give me his dal recipe, which he had simmering inside an electric kettle. Over subsequent weeks I heard of summer pudding made from jam and bread crusts, as well as hooch fermented on hot water pipes (a toxic brew of sugar and stolen fruit, popular around Christmas) which, rumour had it, was stashed for safe keeping inside fire extinguishers.

I could have reported all of this but it was old news to the wing officers, and by then I knew I was on my way out. The prison was outdated and overcrowded by the time I left, with the various retraining programmes and education courses either defunct or impossibly oversubscribed.

On my last day, the library crew splurged on a slice of quiche for me at the garden centre. I taught one final workshop, hosting a small party afterwards for my writers, even though I was the person leaving. We toasted the future with mugs of cola, the men wrapping their slice of chocolate cake in paper towels to transport back to the wings. At the last moment, one of my pupils broke rank and hugged me. “What they going to do, Miss, bang me up?”

When the time came to empty my desk I unlocked the golden egg from my draw, holding it by the stem like a sommelier. The shell was cracked by then, the potato rose had lost some of its varnish. But that didn’t matter. There was, I felt, something fundamentally human about the urge to create art, or bake pie, even in the bleakest surroundings. In my 30s now, I have moved house six times and countries once. The egg sits on the top shelf of my bookcase, technically, I suppose, the property of the Queen.

All names have been changed