The Nelson Stair

The Dulwich Picture Gallery is smaller and simpler and only one architect was involved - Rick Mather, also responsible for the expansion of the Wallace Collection, to be opened next month. But the task was not easy. As a jewel-like little building, fiercely protected, Soane's gallery - complete with its mausoleum to the little group of art dealers and friends who originally donated the collection to the public - was one of the hardest to augment. How to improve a perfect building? Where exactly do you add new stuff like cafe, education room, lecture hall?

Dulwich Picture Gallery

Mather has done it by creating low new buildings emerging from the 18th century garden wall set well forward of the gallery. He links them both to the old Dulwich College chapel alongside and to Soane's building itself, by means of a modern cloister of bronze and glass, so making the start of a quadrangle as suggested by Soane himself in his earliest designs. For all its faint air of early Frank Lloyd Wright, this composition is necessarily understated, and none the worse for that: this is no place to do a Guggenheim.

With Soane's building itself, you would swear, at first glance, that nothing had been done there, that it was the same as ever. In fact, it has been effectively taken apart and put back together inside its shell. This is not the first time. It was modestly extended in a Soanian manner in the early 20th century, and badly damaged by a flying bomb in World War Two, leading to a reasonably sensitive reconstruction and more small additions in the 1940s and 1950s.

Soane's lantern skylights - the first and still the best design for top-lit galleries, copied almost slavishly by architects to this day - have been re-glazed and given adjustable dampers to diffuse and control the light much better. The main rooms have been repainted in the original deep Soanian red - chosen and paid for by Soane after the original colour scheme by another consultant had proved disastrous. The nasty post-war cork-tile floor has been replaced with more suitable broad oak boards. The mausoleum, one of Soane's finest works, has been discreetly tidied of some clutter that had accumulated. Some of the less good 1950s alterations have gone.