He's a fine one to chalk

Antoine Watteau's drawings are expressive gems, says Adrian Hamilton – and the truest measure of his talent

I must confess to having had my view of the French artist Antoine Watteau (1684-1721) changed by the new exhibitions of his work in London.

The two French curators of the stunning show of his drawings at the Royal Academy, Pierre Rosenberg and Louis-Antoine Prat, are of the belief that he remains one of the greatest of all French artists from any time, a view also held by the new head of the Wallace Collection, Christoph Martin Vogtherr, who has organised two Watteau-themed displays there.

I still find that hard to buy. Yes, he was an innovator, creating the form of fêtes galantes that took French painting from the Baroque to the Rococo. True, he was a one-off, an outsider untrained in art who forged his own way in Paris unpatronised by the court. But that doesn't make him a great artist in his own right. Paddling in the shallows between Georges de La Tour and Jacques-Louis David, between Velazquez and Goya, his combination of artifice and knowingness in his renditions of society at play in park surroundings have always left me cold, for all their way with colour and nature.

Not so with the drawings. It was a form which he pursued with as much invention and even greater flare than his painting. It was to him an expression the equal of oils if not better, a means of capturing movement and expression without the intermediation of considered composition. Indeed, he used his drawings not, as was the custom, as preparations for his paintings, but as a resource which he could draw on in the finished oils.

He drew from life, he drew from models, especially women, and he drew in sequence, catching his figures as they changed expression and stance. And he drew in chalk, first just in red, then in red and black, and finally in red, black and white, les trois crayons, for which he was famous.

What makes them not just so lively, but also so forceful is partly the technique. Watteau worked at speed, even in his paintings (which is what has made some of them deteriorate so badly since), hatching in the robes, thumbing the skin tones, conveying movement not just in the line but in the quickness of crayon impression.

It's not that he took much interest in people as such. In none of his drawings, even in the series of Savoyard peasants who came to town in the off-season to earn money through entertainment, or the innumerable studies he made of actors from the Commedia del'Arte and his musician friends, do you feel a past or a story.

Instead, he was endlessly fascinated with dress and gesture, the glances and movement that made people come alive. His way with costume, the manner in which a gown composes itself as the figure sits or lies, the weight of the fabric and the fancifulness of the trimmings is truly breathtaking (Two Studies of a Woman Seated on the Ground is a stunning example). So is his capture of the hands as they grasp an instrument, gesticulate to space or tug at their costume.

It was done with study after study, sometimes in single figures such as the rather mournful figures he sketched of a Persian embassy in the city (or maybe his friends in Persian costume – we don't know for certain) but mostly of several drawings per page.

It was action, and mood, that he seems to have enjoyed most, not the formal studies of the figure and the nude of the academicians (although he became a member soon enough). The exhibition makes a case for the nudes he did, in preparation for his commissioned paintings of the four seasons. But in truth he was unhappy with the Rubens and Titian monumentality of the figure and it shows. Far better are the informal sketches he made of his sitters dressing, or undressing, where his talent for dress and expression could come into play.

The curators say that he destroyed most of these works, as he asked for the destruction of some of the semi-erotic oils of women at their toilet, because he saw they were too risqué. I'm not so sure. I suspect he simply saw them as works in an imposed genre with which he was (rightly) ill at ease.

That seems to have applied to portraits and still lives as well, neither of which seem to have tempted him much. Even a warm, affecting portrait in charcoal of his close friend Canon Haranger has the good cleric drawn twice, once looking straight at you and the other glancing aside with an ambiguous look of wistfulness and expectancy.

Indeed, the most exciting works in this show are the pages where he does several versions of hands, faces or gestures. Whether he was doing it deliberately or not, they form wonderful compositions of fluidity and force. Three Studies of the Bust of a Black Boy displays Watteau's extraordinary way with flesh tones and form, Three Studies of a Seated Woman, in Two of Which She Plays a Guitar shows just what a master he was of drapery as of glance. And if his more statuesque male and female figures can't match the art of the masters, his Head of a Boy and Two Half-Length Studies of a Flute Player and Two Studies of Women, the One on the Left with Arms Raised; the One on the Right Seated, Pulling up Her Stocking, show a vivacity of drawing that few if any other artist ever achieved.

This, as the curators state, is a show that will probably never be repeated, with some 90 of the 660 drawings which survive. Drawings on paper are just too fragile to be shipped about on this scale. Which makes it all the more necessary to go now to this unique exhibition.

Whether you quite feel the same about the paintings you can test by going to the Wallace Collection, which has launched two exhibitions timed to coincide with the drawings. One is a re-hanging of the gallery's own substantial collections of Watteau paintings, and the other is a showing of the works collected by Jean de Jullienne, who produced a four-volume book of engravings of Watteau's works soon after his death.

The Wallace has no less than eight Watteau paintings, to which it has added two other works from Sir John Soane's Museum in London and York Art Gallery. The whole group, beautifully re-hung in an upstairs salon of the house in Manchester Square, includes one Lady at her Toilet and a half-dozen of the artist's signature fêtes galantes.

Of their liveliness there can be no doubt. After seeing the drawings, you can readily appreciate how Watteau drew on his studies of movement and gesture in his grander works of people of society chatting, dancing, reclining, eating and teasing each other, while players stroll among them, in scenes both of humanity but also (Watteau is ever ambiguous in his meanings) of artificiality and fantasy.

He had talent. But a genius? Give me the drawings any day. They are so full of life, they make you feel fond just looking at them.

Watteau's Drawings, Virtuosity and Delight, Royal Academy, London W1 (020 7300 8000) to 5 June; Esprit et Vérité: Watteau and His Circle, The Wallace Collection, London W1 (0207 563 9500) to 5 June