Inside the Factory Season 8 is to Premiere on BBC Two

Gregg visits the Woodmansterne card factory in in Watford. It's one of the largest greeting card companies in the UK, a family business sending out 35 million cards a year.

Gregg Wallace visits a factory in rural Somerset that produces one million pots of it every twenty-four hours, while Cherry Healey helps out with the UK's biggest blackcurrant harvest.

In the second episode of the series, Gregg Wallace visits a sock factory in Leicester that produces one and a half million socks annually.

Gregg Wallace visits the world's biggest cider producer, which produces more than 350 million litres each year.

Gregg Wallace visits a factory in Essex that produces 400,000 cereal bars a day, and follows the production process from the arrival of the ingredients to the eventual dispatch, discovering the importance of getting the perfect balance between honey and glucose. Cherry Healey travels to South Africa to help with the macadamia harvest, where a quarter of the world's supply of these nuts are farmed. Historian Ruth Goodman climbs a mountain in the Lake District to investigate the history of one of the oldest forms of snack bar - the Kendal Mint Cake.

Gregg Wallace visits a liqueur factory in Ireland that produces 540,000 bottles a day. He tracks the journey of a bottle of cream liqueur through the three-year production timeline. At the other end of the journey, Cherry Healey discovers where the empty bottles are recycled. Plus, historian Ruth Goodman visits a monastery to discover the spiritual origins of liqueurs.

In Wigan, Gregg Wallace visits an enormous soup factory, which produces two million tins a day.

Gregg Wallace is in France at an enormous foundry that produces a cast iron pot every five seconds. He follows production of casserole dishes from the arrival of 20 tonnes of crude iron right through to brightly coloured orange pots. Along the way, Gregg tests his mettle by taking a sample of molten iron at 1,550 degrees Celsius. With only a heatproof visor and gloves as protection, he dips a ladle into a bubbling cauldron and pours the white-hot sample into a tiny mould. He also discovers that the coloured enamel they protect their pots with is made from glass.

Gregg Wallace is in Cornwall at an enormous bakery where they produce 180,000 Cornish pasties a day. He follows the production of the pastry snacks from the arrival of two tonnes of swedes right through to dispatch. Gregg learns that there are very specific rules to creating a Cornish pasty. They must be made in Cornwall, the filling can only contain onion, potato, swede, beef and some seasoning - and each ingredient must be cooked from raw within the pastry parcel.

Gregg Wallace is in Nottingham at an enormous party food factory where they produce 200,000 canapes every 24 hours.

Gregg Wallace visits a mattress factory in Leeds, where he discovers how steel is stretched and coiled into springs and the advantages of natural fibres like hemp and wool. Cherry Healey talks to a sleep scientist about the benefits to reaction time from taking an afternoon nap, and Ruth Goodman tries out a Middle Ages mattress made out of a straw-stuffed sack.

Gregg Wallace visits a croissant factory in France that produces 336,000 pastries a day, and discovers how an 83-year-old strain of yeast is used to create the perfect flavour. Cherry Healey talks to a professor who specialises in exploring human senses about the perfect way to eat a croissant and visits a farm that produces concentrated butter that is 99.8 percent fat. Plus, Ruth Goodman is in Paris investigating the croissant's surprising Austrian origins and the role of bread in the French revolution.

Gregg Wallace visits a clothing factory in South Shields that manufactures 650 waxed jackets a day. Cherry Healey investigates the science behind waterproof clothing, discovering how a layer of material can keep rain in while allowing sweat to escape, as well as discovering 150-year-old methods of making umbrellas. Plus, Ruth Goodman visits a Scottish harbour to discover the origins of weatherproof coats.

Gregg Wallace is in Derbyshire at an enormous cherry bakewell factory, where they produce 250,000 of the little tarts a day.

Gregg Wallace is in Gateshead at a cheese factory where they produce 3,000 tonnes of spreadable cheese every year.

Gregg Wallace is in Germany at a historic pencil factory where they produce 600,000 writing implements a day.

Gregg Wallace is in Burton upon Trent at Britain's biggest brewery, where they produce 3 million pints of beer a day.

Gregg Wallace is at an enormous pizza factory in Italy, where they produce 400,000 frozen pizzas each day. Meanwhile, Cherry Healey investigates mozzarella.

Gregg Wallace follows the production of frozen potato waffles at a factory in Lowestoft, and Cherry Healey learns about the differences between waxy and floury spuds.

Gregg Wallace explores the North Yorkshire factory that produces 625,000 sausages a day. Cherry Healey is at the University of Chester getting the scientific lowdown on getting the best banger, and historian Ruth Goodman finds out how German bratwurst became a top dog in America.

Gregg Wallace explores the Manchester factory that produces 700,000 toilet rolls a day. Cherry Healey gets the bum deal of following the flush through the sewers and water treatment works of Brighton, and historian Ruth Goodman finds out what was used to wipe with before the invention of toilet paper.

In this Christmas special, Gregg Wallace visits a factory which produces two million tins of festive chocolate assortments a year. Cherry Healey is producing other festive treats. She travels to Germany - the home of so many of our Christmas traditions - where she joins a crew of 35 ornament decorators, applying glitter and paint to an army of glass Santas. Historian Ruth Goodman is on the trail of the Christmas turkey.

Gregg Wallace explores the Nottinghamshire factory that produces 250,000 jars of curry sauce each day. Cherry Healey helps harvest chillies.

Gregg Wallace is in Derbyshire at an enormous coffee factory where they produce 175,000 jars of instant coffee every day. He follows the production of freeze-dried instant coffee, from the arrival of 27 tonnes of Brazilian green coffee beans right through to dispatch. Along the way he chills out in a freezer cooled to -46 degrees C and discovers how they give you that hit of freshly brewed coffee smell when you pierce the foil lid.

Gregg Wallace explores Ribena's Gloucestershire factory. Meanwhile, Cherry Healey is in the lab figuring out why fizzy drinks are so appealing, and historian Ruth Goodman is working out why we associate barley water with the Great British summertime. The connection dates back to 1934, when the marketing team from Robinson's made up a batch to rehydrate the players at Wimbledon.

Gregg Wallace is in the Netherlands at one of the world's biggest sauce factories. Its annual output is a quarter of a million tonnes of condiments, and more than 50 per cent of this heads to the UK. Cherry Healey is on the trail of another of our favourite sauces - soy - not in Japan, but south Wales, where a factory churns out bottles and sachets of organic sauce to a 2,000-year-old recipe. Ruth Goodman investigates the origin of Worcestershire sauce, as told by Mr Lea and Mr Perrins.

Gregg Wallace explores the Grimsby factory that processes 165 tonnes of fish a week and produces 80,000 cod fish fingers every day. Meanwhile, Cherry Healey travels to Grindavik in Iceland where they land up to 50 tonnes of cod a day. She follows the fish through the processing factory, even trying her hand at gutting the fish. Historian Ruth Goodman is investigating the origins of cod fish fingers. She finds that Bird's Eye were the first to introduce them to the UK, basing them on a US product called fish sticks.

Exploring the fascinating factory processes and surprising history behind our favourite festive treats. Gregg Wallace follows 24 hours of production at a cake factory in Oldham, near Manchester, where this year they will make two million Christmas cakes for Marks and Spencer. Cherry Healey is given special access to Britain's largest marzipan factory, which produces two thousand tonnes of almond paste every year, and visits one of our largest sprout farms where, during the two weeks before Christmas, they pick 190 million sprouts. Ruth Goodman adds her own Christmas revelations by investigating how our early industrial heritage inspired Charles Dickens to write a Christmas Carol, and why we call Christmas tree lights fairy lights.

Gregg Wallace is in London at Europe's largest biscuit factory, where they produce 80 million biscuits every day. He follows the production of chocolate digestives, from the arrival of 28 tonnes of flour right through to dispatch. Along the way, he discovers that the biscuits are shaped by a bronze roller costing up to ten thousand pounds, and that the chocolate is added to the bottom not the top of the biscuits, meaning we are all eating them the wrong way up.

Meanwhile, Cherry Healey is on the trail of that chocolate. At the refinery in Manchester, she learns that it is transported in heated lorries kept at 50C to stop it solidifying on its way to the factory. She also discovers that this is the most expensive ingredient, at around £2,000 per tonne. And she is in Nottingham University's sensory lab, where she finds scientific proof that dunking your biscuit improves its flavour and that tea is the best liquid to dunk in. Cherry takes to the streets to see if that stacks up in the real world.

Historian Ruth Goodman investigates the link between biscuits and digestion. She finds references in Samuel Pepys's diary to biscuits being a cure for flatulence and digestive discomfort and discovers that in Victorian times it was thought that biscuits could cure everything from typhoid to scarlet fever. She also takes a look at an antique biscuit baked at the beginning of the 20th century - one of Huntley and Palmer's notorious army biscuits. These dry hard biscuits were supplied as rations to five million British soldiers on the front line in the First World War.

Gregg Wallace is in Italy, hitching a lift on a train carrying over a thousand tonnes of wheat to the largest dried pasta factory in the world. It produces 60% of all pasta made in Italy and supplies 3,000 tonnes to the UK each year. Gregg traces the journey the wheat takes through a seven-storey mill and into the production zone where it is mixed with water, pushed through moulds and turned into spaghetti. Along the way, he discovers that the perfect string of spaghetti is 25 centimetres long and examines the technology that allows them to produce 150,000 kilometres of it each day - enough to stretch round the earth almost four times.

Meanwhile, Cherry Healey discovers why the best pasta is made with durum wheat. This is a hard wheat that, when it is milled, turns into the granular yellow flour known as semolina, which translates as semi-milled. This is the essential basis of pasta as it retains its shape and texture when cooked. She also helps to harvest 15 tonnes of tomatoes, turning them into 3,000 litres of pasta sauce. Along the way, Cherry is surprised to hear that the British habit of pairing spaghetti with bolognese outrages many Italians. She learns why different shapes of pasta are ideally paired with different sauces and promises in future she will serve her spaghetti with a more suitable topping, like carbonara.

Historian Ruth Goodman discovers that pasta arrived in Britain much earlier than we imagined. She heads to the British Library to look at a manuscript from 1390. It is a cookbook written for King Richard II which contains a recipe for something called lozyns. Ruth cooks up a batch and is convinced that this an early version of lasagne. She also navigates the streets of Soho armed with a 1958 restaurant guide to find out how we first fell in love with Italian food.

Gregg Wallace receives a load of tea leaves from Kenya and follows their journey through the factory that produces one quarter of all the tea we drink in Britain. Gregg turns his 20-tonne batch into 6.9 million bags. Along the way, he discovers that there can be up to 20 different teas in your bag and that the recipe for the blend is altered every day, measured against a standard created in 1978.

Meanwhile, Cherry Healey discovers the secrets of the tea leaf in an African tea-processing plant. She learns that 40% of each leaf is made up of chemicals called polyphenols. She is surprised to find that white, green and black tea are all made from the same leaves. She also discovers that the bag surrounding your tea is not ordinary paper, but a highly engineered fabric made up of hemp, wood and polypropylene. She watches as a 60-kilometre-long roll is produced. And she gets some scientific tips on making the best possible cup of tea with a tea bag.

Historian Ruth Goodman investigates tea adulteration. In the 19th century, there were eight separate factories in London which existed solely to dry and recolour used tea leaves. She discovers that it was 'honest' John Hornim who put that right and ensured we could trust our tea. She also finds that in the military during the Second World War, armoured divisions had to leave the safety of their tanks to brew up - a habit that resulted in many casualties. She climbs on board a modern-day tank to make a cup of tea with a boiling vessel, the innovation that solved this problem.

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

Gregg follows 24 hours of production at the world's largest mince pie factory, where they will make 180 million mince pies this year. As he helps to mix pastry and stew mince, Gregg discovers the challenges of producing 2,000 perfect pies every minute. He also attempts to roll the sponge on the Yule log conveyor belt - with disastrous results.

Cherry travels to south Wales to meet the workers who make enough tinsel in a year to reach Hawaii, and she is given special access to a high-tech factory that produces over 400 million metres of bestselling wrapping paper.

Meanwhile, Ruth Goodman discovers the explosive history of Christmas crackers.

Documentary series. Gregg Wallace joins a human production line in the largest sports shoe factory in the UK to see how they produce three and a half thousand pairs of trainers every 24 hours by sewing 32 million individual stiches and using 140 miles of thread. Meanwhile, Cherry Healey gets hands on in a tannery to help them process thousands of rawhides into finished leather for the nation's shoes, and finds out how a ballet shoe company painstakingly turns 37,000 square meters of satin into a quarter of a million ballet shoes - some of which only last for one performance. She also gets to design her own court shoes at Cordwainers College in London. And historian Ruth Goodman reveals how, when the sewing machine was first introduced into shoe factories in the mid 19th century, traditional shoemakers went on strike, rebelling against joining a restrictive production line. She also traces the surprising origins of the humble trainer.

Gregg Wallace helps to unload a tanker full of sugar from Norfolk and follows it through one of the oldest sweet factories in Britain to see how over 500 workers, as well as some mind-boggling machines, transform it into over a hundred million individual sweets within just 24 hours. He discovers how the factory that produces Lovehearts could be the most romantic in the world because one in four of the people who work there are in a relationship with each other, how they make 5,000 Fizzers a minute using a tablet-pressing machine that uses 3 tonnes of pressure to create each sweet, and meets the man in charge of making three quarters of a million Fruity Pop lollies every day.

Meanwhile, Cherry Healey is let inside the research and development department and experiences for herself how hard it is to come up with a new product, as she attempts to invent her own version of sherbet using citric acid and sodium bicarbonate. She also finds out how they put the letters in seaside rock by making a giant version and then stretching it to the right size, and is given special access to the Fisherman's Friend factory in Lancashire to discover how a local family turned a niche product into a worldwide success.

And historian Ruth Goodman investigates how sweets were first invented and discovers that, in the Middle Ages, they were used as a medicine and thought to reduce flatulence. She also finds out about the human cost of Britain's sweet tooth in the 18th century and how an abolition movement instigated a sugar boycott which helped to end the slave trade.

Brompton's bicycle factory in West London is the largest in Britain, producing 150 of its distinctive folding bicycles every 24 hours.

In the fourth episode of Inside the Factory Gregg joins a multi-stage manual production line to make his very own bike. He'll learn how to put together 1200 individual parts. He'll also attempt to braze a bike frame together using extreme heat of a thousand degrees, a skill that takes years to master. He'll visit a leather saddle maker in Birmingham that's been making saddles for 150 years and discover how they use cowhide from UK and Ireland cows because the cold weather means they have thicker skins.

Meanwhile, Cherry Healey gets some tips from Cycling Team GB to help us all improve our pedal power. She also learns how to paint a bike frame fit for the British weather using an electro-static charge and a 180 degree hot oven. Cherry also investigates why cyclists and trucks are such a deadly combination: in London alone there have been 66 fatalities since 2011 and half of them were collisions with a truck.

And historian Ruth Goodman reveals that folding bikes date back to the 1870's, and how 70,000 folding 'parabikes' were manufactured during World War II, some of which played a role in the D-Day landings. She'll also find out how the invention of the safety bicycle in the late 1880's was used by Suffragettes to ride to rallies and spread the word in their fight for equality.

Today in the UK we get through more than two million cans of baked beans every day, with the average UK household consuming 10 tins of canned food a week. Gregg Wallace helps to unload 27 tonnes of dried haricot beans from North America and follows them on a one and a half mile journey through the Heinz factory in Wigan - the largest baked bean factory in the world - making more than three million cans of beans every 24 hours.

He'll discover how a laser scrutinizes every single bean; how the spice recipe for the sauce is a classified secret known only by two people; and, most surprisingly, how the beans are not baked at all!

Meanwhile Cherry Healey follows the journey of her discarded baked bean can through a recycling centre and onto the largest steelworks in the UK, where she watches a dramatic, fiery process that produces 320 tonnes of molten steel - enough to make eight million cans.

She also takes a can that is 14 months after its ‘Best Before' date to a lab at the University of Coventry and is amazed when tests reveal it has the same Vitamin C levels compared to fresh tomatoes. The lab also proves that a 45 year-old tin of Skippers is still fit to eat.

And historian Ruth Goodman looks at how tinned food was invented to improve the nutrition of sailors to prevent them developing scurvy on their long voyages at sea. She'll also relate how Henry Heinz first marketed baked beans in the UK in the early 1900s - making them a family favourite.

The British love eating crisps. So much so that we get through a staggering half a billion crisps a day - and that takes 17 million potatoes. So why do we love the humble fried potato snack so much, and what are the secrets behind making the perfect crisp?

In the second episode of Inside The Factory, Gregg Wallace and Cherry Healey go in search of these answers and discover plenty of surprising facts along the way.

We'll see Gregg at the largest crisp factory on earth - Walkers factory in Leicester - as he follows 27 tonnes of potatoes as they are peeled, sliced and fried to make more than five million packets of crisps every 24 hours. He'll discover how each bag is filled with nitrogen to keep the crisps from going stale - and if you ever wondered how a crisp gets it flavour then we'll get to see the inside of the factory's development kitchen, where seasoning begins its crisp life as a real food dish.

Meanwhile Cherry Healey discovers the secrets of perfect crisp potatoes, and how it is all down to a potato's sugar content. She also finds out that our noses play a central role in how things taste and ambiance can be as big factor as ingredients. Plus she follows the production of Monster Munch, where the factory transforms 96 tonnes of corn into 12 million monster feet every single day.

And historian Ruth Goodman investigates who really invented the crisp: was it the Americans, as is often cited, or the British? Ruth cooks up the earliest known recipe for crisps to uncover the truth.

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 as it is cooked, milled and flavoured to become Crunchy Nut Cornflakes. He discovers how they can produce more than a million boxes of cereal every 24 hours and distribute them all over the globe. Meanwhile, Cherry Healey finds out about the immunity-boosting powers of vitamin D, which is added to many of our breakfast cereals. She also discovers the effect that skipping breakfast has on our cognitive function - studies show that breakfast skippers perform 7% worse in attention tests. And historian Ruth Goodman sits down to a Victorian breakfast of lobster and pig's head to reveal how the average Victorian was gorging down a mind-boggling four and a half thousand calories a day and that breakfast cereal was invented as a healthy alternative.

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, 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 the production, science and history of bread in Britain.