Interiors: A river runs through it

The powerful rush of water that passes right through the heart of Philip and Victoria Basil's home has a mesmerising quality. It's a constant backdrop but nothing to do with the floods that have struck Oxfordshire and so many other parts of the country of late, but all to do with the particular pleasures of living in a converted water mill. At Beard Mill, the mill race and sluices have become a distinctive part of the conversion, framed by new glass and vintage stone and traversed by an internal glass bridge.

"We didn't want to disguise the fact that this is an old agricultural building," says Philip Basil, who works in the City, "or turn it into something pretentious or twee. We haven't hidden the brick or stonework and we have kept the remaining mill pulleys and anything else we found. We wanted a contemporary style and to keep it simple while restoring the building sympathetically."

The Basils had long thought about converting the substantial and listed mill, which is part 16th century and part 19th century. They bought the five-acre property 10 years ago after moving out of London, and for many years concentrated their attention on the 16th-century farmhouse that stands alongside the mill itself, which was used as ramshackle studios by artists for many years.

But with three young children – Cecily, eight, Charlotte, six, and Freddie, four – there was a desire for more living space. Also, Victoria is a doctor specialising in antenatal screening and wanted to set up a private clinic offering scanning, monitoring and advice for mothers-to-be. The mill buildings offered a perfect opportunity to have a larger home and to provide plenty of space for the clinic.

"We talked about doing something with it for a long time," says Victoria. "The big decision was about whether I decided to work from home and we hovered around that and it took a few years to build up the courage to go ahead with it. For me, it was about trying to offer reassurance in a nice environment and give pregnant mothers and their partners some support."

The ground floor of the mill offered the perfect area for the clinic, with space left over for flexible living spaces. The upstairs offered a vast, open-plan living area, plus a new guest room on the second floor. But for a long time the Basils stumbled over the challenge of how they would connect the mill to the farmhouse.

"I used to sit in the garden in years gone by and wonder how we could do it," says Philip. "Then we got in touch with the architects at Berman Guedes Stretton and they found a way of making it work for us, and we realised that we could get a great working space for Victoria and have a bigger home."

The architects came up with a glass-fronted link between the mill and the main house, making use of an existing garden wall at the back of the new structure. The link offered a new front door and entrance hall, while bringing in more light to the farmhouse at one end and offering easy access to a new stairway at the other end that leads directly into the new first-floor living area over in the mill.

"Philip and Victoria were keen from the start that they wanted this connection," says Jon du Cruz, project manager from Berman Guedes Stretton, who have years of experience in working with historic buildings, including a number of colleges in nearby Oxford. "Although it was one of the smallest parts of the whole job, it was one of the most interesting and challenging. We wanted to leave the stone wall that now forms the rear of the link as untouched as we could, as it gives this wonderful texture and character to the space, while making this simple connection between the two buildings."

Creating the new entrance has not only made the mill easily accessible, but given much more logic to the main house. Before, visitors had always been confused because the main entrance to the farmhouse was tucked away around the back.

"It has really turned the house around for us," says Philip. "The old front door became our back door and everything now makes much more sense. One of the things that we are really pleased about is that we have ended up with such a great sitting room in the main house, where taking out a wall separating it from the entrance hall means we now have much more light coming into the room, yet it's still a cosy place where we can go and sit in the evening."

Back in the mill, things did not go quite so smoothly at first. Although the building had appeared largely sound, when the old corrugated roof came off it soon became clear that many of the original timber beams, roof tresses and rafters were badly damaged and decayed, especially where they met the stone walls. It meant more cost and a great deal of work in repairing the timbers.

"We had a fairly modest contingency budget and that was gone in week one as soon as they took the roof off and saw the state of the timbers," says Philip. "At that point it got quite scary but once we'd started we were committed. It was quite stressful. I was working in the City every day with Victoria looking after things here and I'd get home and almost every day in the early stages would find that something we hadn't known about had cropped up."

But the mill conversion soon began to take shape, finishing on time at the end of 2006 with some months more of tidying up and furnishing the new spaces, with help from interior designer Stella Mannering. The first floor has become a large entertaining space dominated by an impressive French fireplace suspended from the ceiling like a sculpture. This fireplace also swivels, so can direct heat towards the seating area at one end and a dining area at the other. Windows have been kept purposefully bare of curtains to frame the outdoor space as simply and dramatically as possible.

The Beard Mill Clinic opened last autumn while, as planned, the rest of the space has become a spacious part of the Basils' extended family home, which really comes into its own when they are entertaining or when guests come to stay. On occasion, when the children are with their grandparents for the weekend, Philip and Victoria move across to the mill and its guest room and savour the space with only the sound of the mill race for company.

"You can lie in bed and look up through the skylight above at the stars," says Philip, "and hear the sound of the water coming through the sluices. It almost feels like camping outside but then from up there you also have these amazing views out across the fields and the countryside."

For more information, visit bsgarchitects.co.uk (01865 791728)