Just another repeat on the BBC? Not quite: MacCormac Jamieson Prichard’s extension is designed to echo Broadcasting House but it has enough dramatic twists to become an icon in its own right.

It had been the hallowed home of British radio for 60 years but by 1990, the old Broadcasting House was inescapably obsolete. Its tight-knit stone and concrete structure could not accommodate advanced, rapidly changing communications technology. The building’s status did not help matters: it is grade II*-listed and stands in a conservation area hard up against John Nash’s superb All Souls Church with its circular colonnaded entrance and conical steeple.

MacCormac Jamieson Prichard was appointed in 1990 to prepare the building for the 21st century. Its scheme was daring yet subtle enough to placate the planners – it won permission in just six months. The proposal was to comprehensively refurbish the original building and to replace the large, characterless 1960s extension with a new wing that would flow seamlessly out of it. Although deeper than the 1960s wing, the new extension was designed as a proper counterbalance to the original building by echoing its height, its bullnose frontage and its Portland stone facades. It will also be surmounted by an inverted glass spire that responds to the miniature steel mast on top of the original building and at night encircles a bright vertical beam of light 1 km high.

So far, so similar. But as the first phase nears completion, it is clear that MacCormac’s scheme cannot be dismissed as a deferential pastiche of the original. For a start, the narrow existing passageway between the two blocks has been widened out as a gracious civic courtyard. Second, the courtyard will end in an elegant U-curve that is the exact inverse of the two prows on either side and is aligned to focus on the church spire. Third, most of the half-finished building enclosing the courtyard is faced in a modern frameless glass skin.

“Our strategy has been to complement the massive assertiveness of Broadcasting House with equal but opposite effects,” explains Sir Richard MacCormac. “The original building is solid and convex, so we have created a negative void of similar size alongside it, and we have enclosed it within a wall that is concave and light.”

It is this glass skin that is the most radical and subtle element in the building’s external form. Its overtly modern, delicate character has been cleverly played up in counterpoint to the classical, massive stone walls on either side. As well as a curtain wall that encloses the building in conventional manner, this glass wall includes a sheer vertical curtain of glass that floats 1.2 m in front of it. The outer glass curtain’s free-floating character is enhanced by its sharp frameless horizontal edges, just short of the stone walls it abuts. Yet more alluringly, the glass curtain comes with a complex tartan grid in which a dense lattice of off-white fritting is overlaid by a wider rhythm of sharp blue-green incisions.

Inside the refurbished original building, the grand Art Deco spaces of the entrance hall, radio theatre and oak-lined semicircular council chamber and dogleg stone staircases have all been meticulously restored. The rest of the building, where the actual radio production and broadcasting takes place, has been uncompromisingly modernised in content and style. There are no signs of mellow, languorous, curvaceous Art Deco styling here, as these had anyway vanished through WWII bombing and frequent makeovers. Instead there is a bright scarlet wall enclosing the reconstructed broadcasting studios, black ducting panels and silvery louvred metal ceilings concealing new chilled beams. The ambience is sharp, hard-edged and high-tech – in a word, industrial.

“We set out to create a ‘sound factory’, with people moving out of cellular offices into an open-plan culture and working with new digital technology,” says Mark Hines, a director at MJP.

How the finished scheme will look in 2009
How the finished scheme will look in 2009
How the finished scheme will look in 2009

Only in the second phase of development, when the large new wing is built, will the whole architectural composition come into its own. Passing across the new extension at the end of the courtyard and rising its full nine-storey height will be a huge and exhilarating galleria. Overlooking the courtyard through the window wall at one side, it will comprise open malls at various levels with a lofty atrium at one end and bridges leading to the production spaces on either side.

It will also be shot through by open staircases, multistorey voids, double-height cafeterias and several suspended oval pods containing meeting rooms. In this way, the galleria should function as the social and way-finding hub of the extended Broadcasting House. “We knew BBC radio had at least three distinct tribal subcultures covering the World Service, music and news,” explains MacCormac. “So we created an interstitial area between departments where all their paths meet.”

The other main space in the new extension will be the 24-hour newsroom, which will combine TV and radio news and is billed as the largest live newsroom in the world. Conceived more like a dealing floor than a sound studio, it will allow face-to-face communication across its 4000 m2 area. And rising up through the space will be four tremendous structural “trees”, each with three branches supporting the full seven storeys overhead.

As Broadcasting House is the nation’s prime communications centre, MacCormac thinks it is one of the few buildings that should aspire to being that most clichéd concept – an icon. His efforts to achieve this will certainly be appreciated by passers-by and the 44 million viewers watching the TV news. The only pity is that it will not be visible to the 150 million people across the world tuning into BBC radio.

Broadcasting House