Inside the Factory

In this Christmas special, Gregg Wallace, Cherry Healey and Ruth Goodman explore the fascinating factory processes and surprising history behind our favourite festive treats.

Exploring the fascinating factory processes behind Christmas cake, baubles, brandy and more. And why Christmas tree lights are called fairy lights.

In this Christmas special, Gregg Wallace visits a factory which produces a staggering two million tins of festive chocolate assortments a year.

Gregg Wallace, Cherry Healey and Ruth Goodman look at the production, science and history of bread in Britain.

Gregg Wallace, Cherry Healey and Ruth Goodman look at Britain's love of chocolate and visit one of the world's largest chocolate factories in York.

Gregg Wallace, Cherry Healey and Ruth Goodman look at Britain's history with milk and visit one of the largest fresh milk processing plants on earth.

Gregg Wallace receives a load of corn fresh off the boat from Argentina and follows its journey through the largest breakfast cereal factory in Europe.

Gregg Wallace follows 27 tonnes of potatoes from a farm in Hampshire through the largest crisp factory on earth.

Gregg Wallace helps to unload 27 tonnes of dried haricot beans and follows them on a journey through the world's largest baked bean factory.

Gregg Wallace receives some tea leaves from Kenya and follows them through the factory that produces one quarter of all the tea drunk in Britain.

Gregg Wallace is at the world's largest dried pasta factory in Italy, where they produce 150,000 kilometres of spaghetti each day.

Gregg Wallace follows the production of chocolate digestives and discovers that we are all eating them the wrong way up.

How a factory in Derbyshire produces 175,000 jars of instant coffee every day, from green coffee beans to the freeze-dried final product. How roasting alters the chemical composition of coffee. How caffeine affects the body and brain. How climate change is affecting coffee harvests worldwide, and the coffee species that could cope with warmer growing conditions. The history of instant coffee going back to the American Civil War. How passion for coffee led to the founding of the Stock Exchange, auction houses and newspapers.

How a factory in Manchester produces 700,000 toilet rolls a day starting with spruce timber offcuts from Sweden, pulped and rolled onto 1.2-tonne 'mother reels'. How the water treatment works of Brighton remove debris, grease and bacteria to produce clean water in little more than an hour. How a high-tech Japanese toilet addresses hygiene. How waterless toilets could improve sanitation for one-third of the world's population. The history of the modern flush toilet.

How a factory in North Yorkshire produces 625,000 sausages a day, using machines that can fill 600 sausages in a minute. How low and slow shallow frying delivers the best combination of flavour, moistness and succulence. How veggie protein is created from a tiny speck of natural fungus. How a 'meat sock' is the secret to wrapping a Scotch Egg every three seconds. How German bratwurst became top dog in America, and how German immigrant Charles Feltman originated the hot dog. Cooking up a 2,000-year-old recipe for sausages. How the Romans contributed by importing pepper, bay leaves and other spices that spike modern sausages.

How a factory in Stoke-on-Trent produces 250,000 little cherry bakewell tarts every day - from what makes a shortcrust pastry 'short' to the team of 12 precisely placing the cherry on top of every one by hand. How to swerve a soggy pastry bottom when baking pies and tarts at home. How almonds are roasted and milled into almond butter ready for toast. The origin story of frangipane, the fragrant almond filling used in cherry bakewell. How the modern cherry bakewell actually descends from a mistake.

How a factory in South Shields produces 650 water-resistant waxed jackets a day - from 500-metre-long rolls of undyed cotton, to dipping the finished fabric into baths of heated wax, to assembling each jacket from 23 pieces. How a breathable membrane is key to allowing sweat to get out while keeping water from getting in. How a simple wooden stick is transformed into a top-notch umbrella using saws, pliers, and needle and thread - techniques barely changed in 150 years. The history of seamen adapting oil-covered sail cloth into garments.

How a factory in France produces 336,000 croissants every day - from the 21 tonnes of butter, to the 83-year-old strain of yeast that packs a flavourful punch, to the layering of very thin slices of butter between sheets of dough to create the famously flaky texture. How croissants are best served - and eaten. How 'concentrated' butter produced in north Wales enhances the shelf life of croissants. The history of the croissant, thought to originate from 17th-century Austria, and emerging in its modern French form as late as 1906. How bread played a vital role in the French Revolution.

How the world's biggest cider producer makes more than 350 million litres each year - from orchards in Herefordshire, to the mill in Ledbury, to fermentation and bottling at the factory. How grafting is used to create a new sweet apple variety called Scrumptious. How a by-product of making cider - CO2 - is used to make fire extinguishers. The history of the Victorian apple-breeding boom, and recreating one of Queen Victoria's favourite baked apple desserts.

How a Leicester factory makes one and a half million socks annually. What causes smelly feet, and which socks tackle it best. How a cotton spinner in Manchester produces 4,200 miles of yarn every hour. A revolutionary eco-cotton supplier. The history of 1980s sock fashion, and how the 'Kitchener stitch' helped save the feet of British soldiers in the trenches during the Great War.

How one million pots of yoghurt are produced every 24 hours in rural Somerset - from the Friesian cows that provide the milk to the processing, culturing, and packing processes. How blackcurrant are harvested. Plant-based alternatives to milk. Food-safe yoghurt pots made from 100% recycled material. The history of the electric milk float and the contentious origins of the cream tea.

How Woodmansterne produces 35 million greeting cards a year in Watford - from sketching a card design, to creating an aluminium plate for printing, to guillotining the sheets into cards and the final shipping process. Creating a vegan Christmas feast. The history of the year Christmas was cancelled.

How JCB make as many as a hundred iconic yellow diggers every single day in Rocester, Staffordshire, requiring just 45 hours to make a digger from scratch, and consuming 650 tonnes of steel, 170,000 bolts, 5,000 litres of paint and 236 miles of wiring each week.

How the largest malt loaf factory in the world makes the sweet and squidgy cake-cum-bread, a popular teatime treat consumed at the rate of 130 million a year. How a British baking company cooked up the first business computer. How wheat flour was ground the traditional way, until the Victorians' demand for white bread brought about the demise of Britain's iconic windmills.

How Aunt Bessie's produce a staggering 500 million Yorkshire puddings every year in Hull. How wheat is tested before it can be milled into flour. How to cook the perfect gravy for a Sunday roast. The history of the roast dinner, and the art of washing up Tudor-style.

How Jelly Bean Factory make ten million of their colourful little sweets every day in Dublin. The important role glucose plays in our bodies. How one of the ingredients in jelly beans plays a key role in the production of lipstick. The history of jelly and post-war pick'n'mix.

How denim cloth is made, and how Welsh jeans brand Hiut transform it into one of the world's most popular items of clothing - jeans. How zippers are made. How denim is distressed to make a new pair of jeans look old, in environmentally friendly ways. The little-known person who helped shape the design of jeans forever. The history of indigo dye.

In this Christmas special, new presenter Paddy McGuinness and Cherry Healey visit a chocolate factory in Belgium that produces four million chocolate seashells every day. Cherry Healey is also in Belgium, learning the secrets of white chocolate production at the biggest chocolate factory in the world, and Ruth Goodman is in a city with a familiar-sounding name, Saint Niklas, exploring the European origins of Santa.

Paddy McGuinness makes a wonderfully nostalgic trip to the Warburtons factory in his hometown of Bolton where, thirty years ago, he had a Saturday job cleaning the machines. Meanwhile, Cherry Healey discovers how waste bread is turned into beer, and historian Ruth Goodman reveals why white bread was banned during World War Two.

New presenter Paddy McGuinness visits a factory in Lincoln to explore how they make 500 million packs of Quavers every year. Cherry Healey learns how Bombay Mix is made, while Ruth Goodman reveals the wartime story behind our love of cheese flavouring.

Paddy McGuinness and Cherry Healey are in the festive spirit as they join factory workers in Market Drayton producing gingerbread Santa and reindeer biscuits for Christmas.

Paddy McGuinness and Cherry Healey visit a factory in south Wales that produces a whopping 4.4 billion biscuits a year.

Paddy McGuinness and Cherry Healey visit a factory near Scarborough that produces an incredible 80 million chips every single day.