Boggis and Bunce both stared at Bean. Bean took another swig of cider, then put the flask back into his pocket without offering it to the others. "Listen," he said angrily, "I want that fox! I'm going to get that fox! I'm not giving in till I've strung him up over my front porch, dead as a dumpling!"

– from 'Fantastic Mr Fox' by Roald Dahl

Without wanting to ruin one of the greatest stories of our times, I think I could have saved every character in Fantastic Mr Fox – from Mr and Mrs Fox and the kids to those creatively evil poultry farmers – a whole lot of hassle with one quick piece of advice. Farmers: get yourselves some alpacas. If they had, the whole thing would have been wrapped up by page 10, because foxes really, really don't like the goofy-looking South American camelids.

I don't see any real evidence of this as I skirt fields dotted with babbling, ambling turkeys (and the odd alpaca) at the Copas family's Berkshire turkey farm – which, I suppose, is the point. Director Tom Copas, whose father (also Tom) founded the Copas brand, introduced a pair of alpacas (called Sage and Onion) to one of the turkey ranges in 2015 in an attempt to reduce the number of fox attacks. The results were immediate.

"We had one more attack in that pen and that was it," he tells me, as we clamber over a waist-high electric fence and into one of the pens. "We could see the fox had changed its route and was avoiding that pen completely, and once we knew where it was coming from we could defend against it." Following two more fox attacks at the beginning of this season, Copas bought another eight alpacas (Dasher, Dancer, Prancer, Vixen, Comet, Cupid, Dunder and Blitzen) as a deterrent.

Trying to get a closer look at a couple of alpacas is trickier than you might think. While the turkeys immediately head towards us, gathering to gobble and peck inquisitively at my wellies, the alpacas are much warier, preferring to stay partially hidden behind clumps of cover crops. Even so, they and the turkeys don't seem particularly fussed about one another. "It was a bit of a Mexican standoff at first," says Copas. "They stared at each other as if to say 'Who are you?' 'No, who are you?', but these days the turkeys don't seem bothered by the alpacas at all."

It was a bit of a Mexican standoff at first, but these days they all get along fine

Being pretty low maintenance, and living mostly off grass, they don't cause the humans on the farm much trouble, either, which is one of the reasons Copas has been so happy with the alpacas – all of whom are castrated mature adult males ("Grumpy old men, basically," jokes Copas). Unlike the turkeys, which arrive in May and leave in December, they're on the farm all year round, and this, as Copas explains to me, is crucial in preventing the foxes setting up home when there are no turkeys on the farm. "When you're only using the ranges for six months of the year, anything can happen. The cover crops become established and the foxes, which are very territorial, can live in them." With ten alpacas now on-site permanently, this shouldn't prove a problem.

The Copas family have been in the Thames-side village of Cookham for about 350 years, and they've been farmers for the last century. He represents the fourth generation of Copas farmers, though it was his father who founded the turkey business in 1957 after his own pig-farmer father bought him 153 turkey poults (that's babies) to keep him out of trouble.

He raised the birds, sold them by going from door to door in Cookham, and so began a business that would evolve into a leading producer of artisan seasonal turkeys (Copas Very Very Special Turkeys), not to mention a sustainable chicken farmer (The Thoughtful Producer), an events company and a property division. Diversifying into festivals and bricks and mortar may seem like a radical departure, but it makes sense – Copas Very Very Special Turkeys is an inherently seasonal business, with a laser-guided focus on Christmas.

I visit the Copas turkey farm at the end of October, arriving in Maidenhead by train on a morning that's misty and unseasonably warm. This, Tom Copas tells me on the short car journey between the station and the farm, is a problem. The prolonged warm spell means his turkeys, carefully selected to fit into specific weight bands come December, risk growing too big and "nudging up into a different weight category".

Turkey production is a very seasonal business, with a focus on Christmas

There's only one flock of Copas turkeys reared each year, and with good reason. As Copas puts it, "We're producing a top-end product and the market's really only there for it in any kind of scale at Christmas." The team (of around 20 year-round staff, plus another 120 in the four weeks before Christmas) starts calling butchers to take orders in February, and this is used to inform the number of hatchlings they take on in May. No wonder they've enlisted a team of alpacas to help safeguard their annual incomings.

More than 30,000 day-old poults arrive, and all are of the bronze variety – a native breed that, by the middle of the 20th century, had been largely replaced by white turkeys for commercial turkey production, until a small band of farmers decided to start breeding them again in the 1980s.

While all of Copas' turkeys are now free-range-reared bronze, 12 different sub-breeds are used, each growing to a different size and therefore resulting in 12 target weight categories when the turkeys are slaughtered at 26 weeks. This in itself is really important, Copas explains to me, because it means every turkey reaches maturity. This is in contrast to much of the large-scale commercial turkey production, where birds are slaughtered at different ages to hit target weights, which results in inconsistent (and often less desirable) proportions of bone structure, meat and fat.

The new arrivals are kept in a shed under brooding rings for a week to ten days, then, once they're strong enough they're let loose inside the shed, where they stay for six weeks. At this point they're moved to the growing sheds. "We give them a further week here, now on straw bedding, just to get their bearings and figure out where the food and water is, then we let them out to range," Copas tells me. The farm actually uses two models – perma-housing (big sheds, basically) that backs onto open fields, and into which the birds are herded each night; and big, open perma-tunnels with access to range day and night.

Photograph by Jon Hawkins

At 26 weeks, once the turkeys are fully developed, the process of production – slaughter, through to the packaged product being sent out or picked up – begins. Copas and I wander from the farm's central office to the large sheds in which all of this happens. Though hardly as enjoyable a setting as the rolling fields we'd been wandering around in earlier, what goes on in here plays a hugely important role in defining the 'Very Very Special' component of the Copas brand.

All Copas turkeys are dry plucked and then game hung – a niche process that Tom Copas senior, among others, fought to save from being outlawed in the 1980s. Wet plucking is the norm – once killed, the birds are immersed in a hot water bath to loosen the feathers, which are then pulled out by machine. But that, as Copas explains as we walk through the eerily quiet facility – which will become a hive of noise, activity and intensity as Christmas approaches – presents a problem if you're trying to make the best-tasting product possible. "You can't wet pluck and then hang because it'll go off. In order to mature the meat you have to do things in a particular way. To hang beef for long enough to develop flavour, you need to have enough fat in it, and it's the same with turkey."

To have developed that fat – so the turkey effectively bastes itself when you roast it, too – it needs to be sufficiently mature, which also means the skin is thick enough to resist dry plucking. "We've tried plucking them younger but they're like porcupines," says Copas. Once the slaughtered birds have been plucked (by dipping them in molten wax, which is then chilled and pulled off when hardened, taking most of the feathers with it), they're hung on large racks for two weeks. They're eviscerated (that's the removal of the 'pack' of innards, and other associated tasks) after hanging – a process referred to as 'delayed eviscerated' or 'New York dressed' – before being packaged up, ready to be sold.

The end result is an artisan product that, from the point the hatchlings arrive at the farm, is created entirely within an eight- mile radius of the shed I'm standing in. It's a finely-tuned and delicately balanced process that requires meticulous planning and a skilled, dedicated team. A team that now includes ten curly-haired, four-legged bodyguards with a vendetta against foxes.

Can't wait to get stuck into your festive turkey? Here are our favourite Christmas menus around London this year.