Set dressing: Transformed through a series of dramatic yet demountable new elements, this 1930s film studio is now a lively temporary workplace.

Many young architects set up in practice after a period of apprenticeship working for larger firms. In the UK, a discernible generation of emerging designers have cut their teeth with the English High-Tech establishment. Nick Eldridge and Piers Smerin both spent time in Norman Foster's office before forming a partnership in 1998. Their first project, an elegant remodelling of a house in Highgate, showed a poise and maturity that led to it being shortlisted for last year's Stirling Prize.

This project, research and development offices for BTcellnet, was the outcome of a competition and gave the young partnership their first corporate commission. BTcellnet needed a suitable base for its expanding mobile communications R & D operation and decided to adapt an existing building on the site of London's Ealing Studios. This was conceived as a flexible, responsive, short-term (two year) solution while a new building was constructed elsewhere on the site.

Famous for its popular comedies and wartime dramas, Ealing Film Studios was first set up in the early 1900s, on a four acre site in west London. Between 1931 and 1935, the studio complex was rebuilt by theatre architect Robert Atkinson. Buildings are unassuming and robust -- mainly simple steel-framed sheds with brick external walls -- but they originally incorporated state of the art techniques for film production. In 1955, the BBC bought the studios and although he complex remains a lively enclave, its buildings are increasingly unsuited to the technical demands of modern film and television production. The studio owners are currently embarking on an ambitious redevelopment programme to provide space for film production and media-related companies in a series of new buildings planned around the existing main sound stages, which will be retained and upgraded.

Until these new additions are complete, BT cellnet's R & D department occupies part of the existing Centre Block which has been inventively transformed by Eldridge Smerin. Although the buildings exude an air of genteel decay, their basic fabric was fundamentally sound and the internal organization of steel-framed studio spaces proved eminently suitable for adaptation as flexible, open-plan workspaces and studios.

The brief called for a main development studio and presentation suite, together with meeting rooms, offices and support spaces. Underpinning the technical and organizational aspects was the need to encourage creative interaction between mainly young employees engaged in researching new software programs. As this was a temporary solution, it also had to be economical, with any new insertions capable of being transferred to the department's eventual new home.

Externally, Eldridge Smerin's main move is to enclose the two-storey building in a taut fabric screen, supported by a steel frame, which instantly transforms the structure's appearance and also provides an environmental buffer from neighbouring construction work. Light diffuses through the fabric so that after dark, the building has an ethereal, mesmeric quality. A pivotal corner entrance leads to a doubleheight reception area fitted out with a pair of cylindrical towers made from horizontal bands of prefabricated plywood. These sentinel cylinders contain spiral staircases linked to staff offices that nestle under the roof structure like an artist's atelier.

At the heart of the plan is a former studio space, now recast as the main development studio. Within this volume is a quartet of transparent rooms stacked up like fish tanks and enclosed by laminated glass walls and floors held in steel frames. Smaller cellular offices are deployed around this main space, threaded together on a spinal corridor.

Throughout the building, a series of incisions in the internal and external walls frame and define spaces and views. Most of the existing interior has simply been sprayed white to act as a neutral foil to the new elements.

Distinguished by a concern for enlightened corporate placemaking, this modest scheme also has a strong tectonic quality, intelligently exploring how things are made and fit together, as might be expected from acolytes of Foster. Like film sets, all the new parts are fully demountable and can be easily relocated. Given the site's rich cinematic history, this celebration of the temporary seems an especially appropriate and successful architectural response.