VISUAL ARTS: Nolan's; Nolans Agnew's Gallery, London

Sydney Nolan, who died in 1992 aged 75, is one of Australia's better-known artistic exports. By the end of his life, however, he had lived in England for more than 40 years and acquired all the gloss of the English art establishment: a knighthood, the Order of Merit, membership of the Royal Academy and a gallery in Old Bond Street, London. Five years after his death, that same gallery is mounting an exhibition of paintings from the artist's estate, billed as "Nolan's Nolans" - the works that he wouldn't let go, or which he bought back over the years, to remind him of who he was. The best sort of retrospective, in other words, compiled from the pictures which meant most to the old man himself.

That's how it's billed, but Nolan was famous for painting bad pictures as well as good ones, and alongside key early works (such as Giggle-Palace of 1945, a portrait of the artist as a small boy with his parents on the seafront of the Melbourne suburb where he grew up) and important later ones, like Kelly and Armour of 1962, a picture which fuses so many of the ideas that dominated his life's work, there are a large number of lesser pictures that don't quite fit the bill.

The current exhibition of 87 paintings (by far the biggest show in this country since that at the Whitechapel Art Gallery in 1957), selected from several hundred still in the estate, attempts to show Nolan at his best, but the few great works only make the mediocre ones look worse than they really are. According to Nicholas Usherwood's excellent catalogue, four of these (titled Bather) were painted on the same day in 1945; each in no more than a couple of hours, and they look it. They are priced at pounds 180,000 for the four, not bad for a day's work, but not so good for the artist's long-term reputation. This is the problem that faces artist's estates, especially those of a prolific painter like Nolan who painted some 4,000 pictures and rarely threw anything away: how to protect a reputation when even the minor works command huge prices? It would take a very brave man to insist that some pictures remain hidden from public view.

By far the best paintings here are grouped along one wall of the upstairs gallery. They are mostly landscapes, painted in the late 1940s in Ripolin enamel on very smooth board. This thin, liquid paint dries to a hard veneer which was well-suited to Nolan's depictions of the brittle, brilliant light of the outback. They are deeply atmospheric pictures of red earth and blue skies with an unsettling mood which may have something to do with their often autobiographical nature. Sometimes of a psychological sort - the stark blues eyes of Hare in a Trap, Nolan recalled, were those of his father - or more simply from his ability to freeze and seize a remembered moment - his "blink vision", as his friend Albert Tucker put it.

This exhibition is subtitled "A Reputation Reassessed" - "In making the selection from Nolan's own Nolans," states the catalogue introduction, "it has been our intention to choose only works of the highest quality and thus to do justice to the achievement and reputation of an artist who has not always been well served by a sometimes indiscriminate display of secondary paintings." An admirable purpose, but not quite true to the final result. In fact, what we have is a much more honest display of a talent, which is revealed as much by mistakes as by successes. It's a fine show which confirms, rather than reassesses, Nolan's reputation as a painter of uneven, but occasionally remarkable gifts.

To 25 July (0171-629 6176) Richard Ingleby