And the same is true of even the most apparently conventional, unmistakable bronzes. Take the wonderful rough-cast heads of Emily Young. Young has made her formidable reputation almost entirely as a stone carver in the great tradition. But all her works here are in fact cast in bronze, given a very dark, almost black finish. At a glance you might think they were carvings in one of the very dark marbles she sometimes uses, with their ability to be either smoothed to a high gloss or left ragged and unworked. And though these are all casts from carvings, unpredictably they undergo a subtle transformation in their bronze versions, faintly reminding one, as the carved versions never do, of Igor Mitoraj's virtuoso monumental bronzes.

But in any case, bronze is a highly familiar material, in constant use for artistic purposes at least since the Renaissance, when they trawled some ideas from Classical Greek practice and made them their own. We know what to expect from bronze, even if, as Charlotte Mayer demonstrates, we do not always necessarily get it. But these days we cannot expect that bronze will be the only metallic material around. Indeed, right here in the garden we can find an incredible variety of metallic materials used with great ease and panache by the artists concerned.

When we reach the head of the succession of ponds we come upon, at the bottom of a little sheltered dell, three unmistakably organic forms by Mike Savage. They carry such inorganic titles as Propellor, Twisted and Twisted Split, but the inspiration is clearly from seed pods, two of them closed and still carrying their seeds, and the other, Twisted Split, having presumably burst open to distribute its contents to the winds.

But the thing is, they are all made self evidently of metal. Twisted Split is in copper, which, fairly enough, blends in with the predominant autumn colouring of the surrounding woods, but the other two are made of aluminium, and aluminium-coloured aluminium at that. They ought to stick out like a sore thumb, but somehow they do not. Maybe we momentarily think of Invasion of the Body Snatchers and wonder if aliens may have landed. But whatever planet they come from, they are unarguably reflective of nature rather than the foundry.