Henry Moore, Tate Britain, London

The town-square monoliths of his late period were far from the sculptor's finest work, as this retrospective shows

On the night of 11 September 1940, Henry Moore was trapped in Belsize Park Tube station by German bombing; the so-called Shelter Drawings, which he began the next day and continued throughout the Blitz, were to be his best known and best loved works.

They mark both the mid-point of his career – Moore was born in 1898 and died in 1986 – and the high point of his style. Not long before, his art had struggled to find a voice different from Gill's or Epstein's or Picasso's or Dali's. Not long after, with abstraction discredited by Sir Kenneth Clark, Moore turned, in the public mind at least, into a civic artist – chief of those sculptors whose work, found in New Towns from Basildon to Peterlee, would be derided by Tom Wolfe as "turd in the plaza".

The Shelter Drawings, made in the brief gap between these two histories, are Moore's finest hour.

They also sit at the middle of a new show at Tate Britain, charged with making us think again about the most famous British sculptor of the 20th century. This is always a worrying ambition, awash with the sound of babies being thrown out with bathwater. In the Tate's show, our change of view is meant to come from the revelation that Moore had sexual urges – a truth so self-evident from his work that I can not think why we're being told it. The accompanying catalogue also suggests that Moore may have based elements of the original Shelter Drawings on photographs in Picture Post magazine. Since this (by no means new) idea directly contradicts the artist's own account of how the works were made, the Tate clearly frets that we may go away seeing Moore as a fibber. For what it's worth, the evidence does seem to show that the Shelter Drawings were based on photographs as well as on sketches, which is to say that Moore, being an artist, mined different sources and touched up history. To which one can only say: and?

More annoying is the Tate's effort to turn this imagined flaw into a spurious radicalism. If Moore used photographs, runs the argument, then it was because he was so modern: it was a decade before Francis Bacon would use them. Actually, one thing that comes through loud and clear from this show is how strangely un-modern an artist Moore was, certainly when compared with Ben Nicholson.

As he sheltered in Belsize Park station that night in 1940, Moore knew of the genuinely radical art going on over his head. Two nights earlier and two streets away, the Dutch abstract painter, Piet Mondrian, had been bombed out of his studio. (He sailed for New York shortly after.) Other ambassadors of the European avant garde – Naum Gabo, Laszlo Moholy-Nagy – had also settled in Moore's street, lured there, like Mondrian, by Nicholson and his wife, Barbara Hepworth. Where Hepworth and Nicholson were hugely influenced by the radicalism of these refugees, though, Moore stayed at heart a British artist. Like Paul Nash, his vision started from a kind of English lyricism, hinted at by the names of the materials he worked with: Cumberland alabaster and green Hornton stone, cherrywood and elm.

This is not to belittle Moore, but nor is it to over-sell him, as the Tate does. Until a couple of years before the Shelter Drawings, his work had tried to look outwards and, as often as not, it had failed. His "primitive" sculptures of the 1920s don't set out to be African or Mexican; they aim to be Picasso. (Under one sketch of a carving from New Guinea in the British Museum, the young Moore has inexplicably written "Negro".) Equally, and following a brush with Surrealism, his work of the mid-1930s has a strong feel of Dali. After 1945 and his reinvention as a public artist, much of Moore's sculpture feels either pedagogic (Atom Piece) or kitsch (Rocking Chair No. 2). Relatively little of his work can usefully be called great, and much of that dates, like the Shelter Drawings, from the war years.

It's hard not to feel that history made Henry Moore successful, and that success didn't always suit him. For a glimpse of what he might have been without it, we can turn to the six large figures he carved in elm between 1936 and 1978, works he largely kept or sold to friends. They have a beauty to make you weep, a beauty that is all Moore's own.

To 8 Aug (020 7887 8888)

Next Week:

Charles Darwent sees Richard Hamilton's work at the Serpentine, a nod to the grand old man of British agitprop