Mike Dade, Build It magazine’s planning expert, adds: “In the vast majority of cases, I am convinced people would never get planning permission to significantly extend a rural barn.”

The Seymours decided to extend the barn as simply as possible, to make it about three times its original length. Ed didn’t want to fall into the trap of trying to make the interior of the extension look old, but he was keen to establish some kind of continuity. So he used the same oak flooring as in the first part of the conversion and installed rafters at exactly the same width apart and stained to match those of the original barn.

Ed and Marianne then painted the plastered walls brilliant white to provide a bright, expansive surface on which to hang pictures. From the outside, it is virtually impossible to tell that the property has been extended.

Although the extension looks very modern from the inside, it was actually constructed using simple techniques. Costing a total of £120,000, it consists of a breeze-block structure with traditional Wiltshire stone on the exterior. Luckily for Ed and Marianne, they found a great deal of the stone on their land, which saved a lot of money. The Seymours incorporated a kitchen, a large dining area and a suspended first floor to act as an office.

However, even architects make mistakes, and they had to make some expensive changes. The couple initially incorporated a large overhang on the first floor that led to a dormer window, but decided it looked too conventional and ripped it out.

“Architecture is such an expensive art,” Marianne says, “but if something isn’t right and you’ve got the money, you have to change it.” They also included two extra bedrooms, an en-suite and a utility room.

Internally, every element had to earn its keep. The wall around the new kitchen acts as a very shallow cupboard that’s perfect for tins. The kitchen worktop is made out of zinc, and Marianne says: “The company that made the worktop was reluctant to provide it for us as zinc marks badly, and they were concerned we would moan.”

Ed and Marianne convinced the company that they wouldn’t complain, and love the distressed look of the metal. They were also so impressed with the wood-burning stove they had installed in the initial conversion that they introduced another one when they extended the barn. Ed says: “These stoves are produced by a Danish company called Rais, and are so economical.”

The kitchen and dining area is floored with limestone provided by Stone Age. Ed explains this holds the key to their look: “The floor was expensive, but sets everything else off beautifully. It makes all the fittings look exclusive, even though they’re constructed out of painted MDF.”

This just goes to show that with careful planning a distinctive look can be created on a restricted budget. Ed and Marianne’s style also hinges on restraint — there is no room for clutter and everything must be able to be “put away”. There are invisible cupboards everywhere, to keep the architectural lines clean and house necessities that would detract from the decoration.

A year after the extension was completed, the Seymours decided they wanted to develop further — and more boldly. They submitted plans to introduce a dramatic glass garden room with a sharply angled roof, but were told by the planning officer that they couldn’t add an extension to a barn. Marianne recalls: “We explained that we had already extended once, and the officer was gobsmacked — he assumed that the new area of our home was part of the original barn.”

Having allowed the original extension, the council now gave permission for a new garden room. Ed and Marianne wanted to be able to open the doors entirely, giving the feeling that you were actually outside, although they were concerned that sliding doors would be difficult to proof against weather and draught. Eventually, Ed came across a German company called Solarlux.

“They prefabricated the whole garden-room structure, incorporating a unique door-opening system, and then shipped it over,” he says. “This is a company I couldn’t recommend highly enough.”

At a total cost of £30,000, the garden room was an excellent investment — Ed and Marianne extended their central heating, thus making it a living space for all seasons.

Ed is remarkably relaxed about the fact that the council allowed him to put a dramatically angular glass extension on a rustic barn, probably because he is accustomed to taking a calm and measured approach. “I’ve done one or two other rural conversions and got away with things I thought might have been difficult,” he says. “I’ve never had a problem getting permission. I take the planners into my confidence at an early stage, often before I’ve put pen to paper. What are their concerns? How can I do what I want without upsetting them?” And it’s worked again. Ed and Marianne have now added another extension to their home, this time what Ed calls “a modern interpretation of traditional buildings”, and it gives them two more bedrooms, two more bathrooms, a second living room and yet another Rais stove. They’ve also just bought a piece of land in Sri Lanka, where they plan to build an ultra-modern home.

• Taylor Seymour Architects, 01666 577 777, email info@taylor-seymour.com; Rais stoves’ UK distributor: JU Petersen, 01865 326 364, www.rais.co.uk; Stone Age, 020 7384 9090, www.estone.co.uk; Solarlux, 01924 204 444, www.solarlux.com

• The Sunday Times Building Your Own Home book, edited by Catherine Monk (Hamlyn, £25), is available from Sunday Times Books First for £20 with free delivery. Call 0870 1658 585

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