Architecture: History comes and goes on wheels: After 200 years, Abingdon Museum is still a model of flexibility, writes Peter Dormer

Abingdon Museum's collection is not in the British Museum class, but the building in which it is housed is special. It was constructed by one of Sir Christopher Wren's master masons, Christopher Kempster, and shows the influence, and perhaps the hand, of Wren himself.

Sir Nikolaus Pevsner wrote: 'Of the free-standing town halls of England with open ground floors, this is the grandest.' The building, about eight miles south of Oxford, was built in the late 17th century and served three functions. Its cellars were warehouses; the ground floor was a covered market; and the first floor, which today houses the museum, was a courtroom.

As a scheduled ancient monument, the building is under the guardianship of English Heritage, but is run and maintained by Oxfordshire County Council. As far as the council is concerned, flexibility remains the key to the building's usefulness. When the designer Erik de Graaff was commissioned by the local authority to refurbish the museum he was told that the space would also be used for other activities, including concerts.

De Graaff, Dutch-born but living and working in London, liaised with the curator, Emily Leach, the prime mover in getting the refurbishment in train. The result is a small but excellent example of how to give an architecturally precious space an extended, modern use. Obvious improvements were needed, such as removing the clutter of cases and blinds that obscured some of the tall windows which give the interior its stateliness.

The first challenge was finding a way of clearing the museum space quickly and efficiently. De Graaff designed a display system of six oak and glass 'tower' display units and 12 oak and glass horizontal clusters of cases. These are designed in the form of chevrons. All the cases meet stringent lighting and conservation requirements.

Each unit is mounted on a steel frame and castors that enable staff to move and pack away the museum in two hours without taking apart the arrangements. The chevron design allows the cases to be tucked into one another for storage. De Graaff's word for this process is 'congesting'.

In a further stage of the refurbishment, De Graaff has designed a folding chair which might become a classic of its kind. The oak and neoprene chair folds to a profile that is just 8cm wide, can be opened and closed almost as easily as shaking out a handkerchief, has a generously wide seat, and is absolutely stable. Forty of these marvels have been ordered for the museum.

De Graaff's inventiveness was further revealed earlier this month with his new collection of sculptured chairs and chaise-longues. The collection, called Truss, is made of 6mm-thin medium-density fibreboard. In sheet form, it is almost like paper, but De Graaff's deft engineering design and the application of 'less is more' philosophy has resulted in a series of light, immensely strong seating sculptures. Wren would probably have enjoyed the intelligence and recognised the proportions.