THE WEDNESDAY BOOK: Portrait of painter who was not the Ripper

FIRST, THE bad news: Walter Sickert was not Jack the Ripper. If his life was wayward, posthumous opinion of the artist has been no more predictable. The typically perverse source of the painter-as-homicidal maniac canard, for example, turns out to be one of his descendants.

The thesis was widely aired by American crime novelist Patricia Cornwell in Portrait of a Killer. It is crackers. Sickert's name was never associated with the crimes during his lifetime. This was unsurprising, as he was resident in France throughout the period of the Ripper's activities. One imagines Sickert regretting missing the fuss and infamy that an allegation might have caused, though his womanising, bad temper and proneness to debt produced enough of both.

Now the good news - and plenty of it on every page of this magisterial, taut and fresh book. Sturgis cut his biographical teeth on the briefest of artistic lives: Aubrey Beardsley, who died aged 25. He has now, arguably, discovered his ideal subject. It is a measure of how impressive his rendition of Sickert's life, career and influence is that it feels more apt to argue that the artist has been fortunate in his biographer.

However uncertain Sickert's reputation may be today, it is important to remember that there was no real heyday. His pictures have never attracted a fraction of the sums now lavished on anything Pre-Raphaelite. Still, Sickert's introduction of Impress- ionist themes and approaches to the narrow world of the London art scene was of seismic importance. It would sweep away the aestheticist tendencies of Sickert's first mentor, Whistler, just as decisively as Whistler's influence on Sickert was displaced by that of Degas.

Moreover, the legacy of Sickert's brutal Camden Town Group realism may be seen in a trajectory of many of the most important postwar British painters: Bacon, Freud, Auerbach, Hodgkin. When we are presented with a selection of Sickert's best works he strikes us as fundamentally contemporary. The same cannot be said for any of the Bloomsbury artists.

Sickert turns out exactly what Sturgis claims: "a great man and a great artist". Error and conceit, of course, are just as capable of great size as virtue or truth. There is a good deal less than palatable about the man, and Sturgis spares us nothing. What he achieves is strikingly comparable to the grim truthfulness of his own subject's most effective paintings.

Reading these 760 pages, you approach the art with greater insight, and the man with more interest. As period context is a special strength, to stroll around London in the wake of Sturgis's research offers many new and diverting delights.

The reviewer is writing a life of Ronald Firbank