Made in Britain: At home with the first family of design

David Mellor is one of the great names in British design, the iconic creator of everything from teapots to traffic lights. And with his son Corin now at the helm, the company he founded continues to go from strength to strength. Charlotte Philby pays a visit to Derbyshire to discover how the family lives behind closed doors

It is Good Friday in the Peak District, and a narrow crack of sunlight is straining through heavy rain clouds. Below, in a deep fold of Derbyshire countryside, a railway track runs neatly alongside a sprawling estate, on its path from Sheffield to Manchester. This lush valley was once home to a gasworks near the medieval village of Hathersage, but today it is the industrial hub of the David Mellor enterprise, and home to three generations of a world-famous design dynasty. The head of this empire, the Royal Designer for Industry and a celebrated craftsman – best known for sleek, robust cutlery – is David Mellor CBE, who settled here in 1990, with his wife, Fiona, a biographer and cultural historian. They were followed by their son, Corin, along with Corin's wife, Helen, and the couple's four year-old son, Hector, who have since taken up residence here too. Now with a design museum, shop, café and cutlery factory in the grounds, this is much more than a straightforward family home. Corin explains that the family were keen to introduce the public to their design concept, "so it made perfect sense" to create a visitor centre here, where the Mellor magic actually happens.

Corin, now 42, has been creative director of the Mellor brand since his father's retirement in 2005. It's quite an inheritance: David Mellor, who opened his legendary Sloane Square shop in 1969, originally trained as a silversmith. Yet, though he is renowned for his practical, modern stainless-steel and silver cutlery design, his personal repertoire is expansive. He fashioned the traffic light as we know it, and the controversial square postbox. Combining aesthetics and functionality is David's forte, and he is notoriously passionate about craftsmanship: he personally oversaw all aspects of his projects, from conception to production. Now his son shows equal commitment to the cause. Corin dismisses the idea that having your home open to the public seven days a week might be, at times, invasive. "You shouldn't have to completely divide your time between work and pleasure," he says. "Your work should be your pleasure."

The Mellor home, like the company's products, is both stylish and practical. Inside a gritstone building, a vast hallway lends focus to an intricate steel staircase, designed and engineered by David. This leads up to a spacious kitchen-cum-dining room, all of 22 metres wide. With pitch pine floorboards and matching window fittings, it is a bright, voluminous space, with minimal decor and oozing with natural light. "Because there are windows all the way round the room, you get a real sense of the outdoors," says Corin. This "oneness" with the natural environment requires little embellishment and, accordingly, the décor is minimal. At the centre of the room is a large, utilitarian David Mellor dining table of galvanised steel with a beech top – the same style can be found in their factory where the tables are used for metalwork. On the walls hang two self-portraits, one by Alan Jones, the other by John Bratby, and a 1960s abstract painting. There are two Alvar Aalto chairs and a dark grey leather sofa by the contemporary British brand Hitch Mylius. "For this space, we wanted to create something simple and sophisticated," explains Corin, "and the same treatment goes for the adjoining room."

The adjoining room is a space of identical proportions. Linked to the living area by a bridged glass walkway, it is lined with thousands of books on low shelves. Light streams from a skylight running the length of the room. Again, wood features strongly, "connecting the interior with the outdoors", which is visible through a series of round and semi-circular window openings. This room is officially known as "the library" but also serves as an office, while two double bedrooms are hidden beneath the living area next door. These ground-floor bedrooms are neat, "non-descript" areas, in Corin's words – white with wooden floorboards. "The idea was an upside-down house," he says. "We wanted to focus on a big communal space upstairs, with lots of natural light, where we would spend most of our time."

The family home lies at the far end of the estate, and is reached by a long gravel driveway. Set 500 metres back from this track is another striking building – the circular, lead-roofed Round Building. Once forming the foundations for the gas cylinder that supplied the gasworks, it was transformed in 1997, when the architect Sir Michael Hopkins devised a purpose-built factory for the Mellors to produce their famous collections. The Round Building is now itself an award-winning icon of modern British design – and its details were largely hand-crafted by those working in the factory. "Hopkins gave us a concept," says Corin, "and we detailed the interior – the lights, tables, even the guttering."

Corin is immensely proud of what has been created in this remote corner of Derbyshire countryside. He and his father, he says, share a passion for "enduring, purist design that isn't trying too hard. We aspire to create objects that stand the test of time, that aren't disposable. Neither of us is interested in passing trends." Their work, famous for marrying modern design with classic sensibilities, is testament to this philosophy, and their estate is no exception. Though aspects of it were built centuries apart, there is a distinct harmony between the old and new. Hidden behind the modern Round Building lies a series of cottages, built at the turn of the century, all made from local gritstone. The first is now a small development workshop, and a Country Shop exists in what used to be the gas workers' offices.

Beyond the shop is the David Mellor Design Museum. Again, Sir Michael Hopkins devised the concept, and the Mellors personally implemented the design. Inside, examples of Mellor's traffic light and pillar box are bolted to the slab floor. Otherwise, the décor is understated. "The idea was to reflect some of the design qualities of the Round Building," Corin says. "We kept the interior reasonably calm, because objects inside are what is most important."

This is a recurring theme on the Mellor estate. Here, beauty is found in simplicity; nothing is overly stylised or unnecessarily complicated. This not only allows the objects on display within the centre to stand out, but gives space for the natural beauty of the land surrounding it to flourish. The real focal points of the museum are the wide glazed windows, in front of which stands a long pitch-pine bench. "It's a pretty special feature," remarks Corin, turning his back on the artefacts behind him. "On a hot day we open all the windows, and it's just like being outside."

The David Mellor visitor centre is open from Monday to Saturday, 10am to 5pm, and Sunday, 11am to 5pm. For details call 01433 650 220 or visit davidmellordesign.com

Top ten David Mellor designs

1953 'Pride' cutlery

Designed when David Mellor was still a student at the Royal College of Art, London, this was included in the first Design Centre Awards in 1957. Still among the company's most famous ranges, it has been in production for more than half a century

1963 'Embassy' teapot

As part of a large-scale Government commission, Mellor designed handmade silver tableware for British embassies. The most beautiful teapot ever?

1966 National traffic light system

Perhaps Mellor's most famous industrial design, it was commissioned by the Department of the Environment and is still in use throughout the UK, four decades later

1975 Outdoor seating

With a tubular-steel frame and steel-wire seat, this pleasingly curved structure makes a surprisingly comfortable resting place. Designed by Mellor for Abacus, it won a Design Council Award in 1975

1977 'Chinese Green' cutlery

Made of stainless steel with acetal resin handles in a vivid colour scheme, this was an iconic design of the period and won a Design Council Award in 1977

1998 'Transit' folding trolley

Made of injection-moulded plastic with a chromed steel frame, this stylish, collapsible trolley was designed by David and Corin Mellor for Magis of Italy. A smart, smooth-running piece of mobile furniture for modern urban living, it is already hailed as a design classic

1998 Birch plywood table and stool

Corin Mellor's modern sculptural furniture in bent birch plywood has been widely copied

2007 'Linear' table glass

These hand-blown glasses with diamond-cut lines and beautiful purist shapes have an added decorative element, reflecting Corin Mellor's admiration both for robust English 18th-century glassware and mid-20th-century Scandinavian designs

2007 Black-handle kitchen knives

With ice-hardened blades and acetal-resin handles, these incredibly sharp and well balanced knives required advanced technology in their manufacture. There were 20 prototypes before the final design was approved

2007 Advent wreath

Made of stainless steel and anodised aluminium, this giant metalwork was designed by Corin Mellor to hang in Sheffield Cathedral. A constructional tour de force, it consists of 32 slim bars hanging from the building's roof and was inspired by its architecture. In all there are 380 separate handmade components in the work