The 70s block had a big useless elevated outdoor terrace, doubtless originally envisaged as a modern Hanging Gardens of Babylon, a verdant street in the sky, by the Brylcreemed walkway planners of the 1960s. All Mather has done is to take a section of this redundant space, giving onto a newly-pedestrianised square to the side of the building, and splice in a new building. This gives you, in one, a new entrance foyer and café on the ground, a curving stair and lift to the upper level, an education room, a big new rehearsal room, and some offices. It is a sizeable chunk of a larger Mather rescue scheme going back several years - there's something about Hammersmith that stifles these things - but it works as a set-piece in its own right. Mather has worked his horizontals and verticals, slyly subverting the lumpen lines of his base material, transforming it into a building which - with its brightly internally-illuminated glass walls - acts as a great big sign saying: Theatre!

The next stage, starting immediately, is for the square outside - just a big bit of leftover road space - to be given some character by the excellent Edinburgh-based landscape architects Gross.Max. Upon which this long-vandalised corner of London (weep at the devastatingly banal, gargantuan 1980s Hammersmith Broadway development a few steps away) will show some small signs of returning civilization.

So on one level, the story of the Lyric might seem to be about nothing more than a neat little extension to a fine producing fringe theatre by an undeniably clever architect. On another level, it is a parable. It contains within itself the history of British cities over 40 years, from megalomaniac "comprehensive redevelopment" to New Urbanism, from Car is King to Car is Crime. The Lyric is consequently not insignificant. Its story is a big one, and it is by no means ended yet.

Rick Mather Architects: http://www.rickmather.com