Exhibitions: All this from just pounds 25

The National Art Collections Fund is thriving, as is proved both by the exhibition now at Christie's and its membership figures. David Barrie, the NACF director, tells me that more and more people are joining. He now has 60,000 members, a 63 per cent increase in two years, and aims for 100,000 by the new century. I think I know why the NACF is suddenly popular and am glad to pass on a tip to IoS readers. The basic subscription is pounds 25, though of course they would like you to give more. In return you get a number of benefits. The most attractive of them is free admission to public galleries that charge an entry fee. There are now no fewer than 170 such museums, and the number is set to rise. So for regular gallery visitors this pounds 25 looks a bargain.

Barrie is quick to add that people who join for this simple financial reason then find that they become interested in local NACF activities. Here's another example of the "stakeholder" attitude of the late 1990s. You pay in a roundabout way for things that ought to be free and then you imagine that you own them. Anyway, it's clear that the major work of the NACF is conducted by a small group of people in London whose expertise is in the high politics of collectors, sale rooms, export licences and so on. Significantly, the Christie's exhibition shows off million-pound purchases while also drawing attention to more provincial concerns. Here are the "Becket Casket", saved for the V&A, the beautiful Claude known as The Enchanted Castle, which now belongs to the National Gallery, the Fitzwilliam's lovely little Renoir; but we are also invited to look at a teapot from the Worcester Museum of Porcelain and a lustreware jug which is now the property of the Sunderland Museum. And very nice they are too.

The show contains around 150 paintings, sculptures, drawings, photographs and artefacts which entered some 50 public galleries in the last 15 years with aid from NACF funds. I found it genuinely impressive. The exhibition is titled "Treasures for Everyone" - and all visitors will have the impression of deft and widespread philanthropy. Considered purely as an exhibition, "Treasures for Everyone" doesn't make sense, since its organisers were keen to stress the variety of the work that the NACF supports. It's an anthology to the nth degree. But when you think of the collections to which the exhibits now belong you get a sense of the extraordinary museum culture we possess, not just in London and provincial capitals but all over the United Kingdom.

The old joke is that Londoners believe the north of England begins at Watford. The Watford Museum has no great fame, but it's not a negligible place and now has the added interest of a tender portrait of his wife by Sir Herbert von Herkomer. This was an appropriate acquisition because Herkomer ran a once-famous art school just down the road at Bushey. The asking price for the picture was a cheapish pounds 1,850, not a big sum but still a little beyond Watford's means. So the NACF came in with a contribution of pounds 462, and now the painting is saved for the people of south Hertfordshire and their visitors. Not a dramatic story but a significant one, for this is obviously the pattern of NACF assistance throughout the country.

The big museums become even more majestic, the smaller ones more interesting than they were. On the evidence of this show, I guess that local museums ask for help when buying artefacts and don't put in bids for paintings, especially if they are by living artists. I also suspect that provincial galleries don't want to buy new British sculpture - a mistake, because it's inexpensive even when of high quality. Modern sculpture at Christie's is the weak part of the show. Here's an overpriced Baselitz wooden figure (Scottish National Gallery of Modern Art, pounds 242,000; NACF contribution pounds 20,000).

A more notable Tate acquisition is Max Beckmann's Carnival (pounds 400,000; NACF pounds 6,000), which fills a gap in the modern German collection. The Tate has also bought Lucian Freud's Standing by the Rags (pounds 920,000; NACF pounds 100,000). The Birmingham City Art Gallery has received Gillian Ayres's Midsummer Night (pounds 21,000; NACF pounds 10,800), and the Scottish National Gallery of Modern Art a magical Picasso collage for pounds 4m (NACF, pounds 150,000). I give such figures because they show that the NACF, with the galleries it serves, is to a large extent at the mercy of the art market. It will take very many pounds 25 subscriptions to buy even a mediocre Freud. As in society as a whole, the gap between the poor and the extremely rich appears to be growing - and in this situation philanthropy is only of limited help. `Treasures for Everyone': Christie's, SW1 (0171 225 4800), to 26 Jan. The NACF can be contacted at Millais House, 7 Cromwell Place, London SW7 2JN (0171 225 4800).