I had a theory about Joseph Mallord William Turner. At an exhibition of his work at the Tate some years ago I noticed a pair of his spectacles in a case with other implements, and the lenses were noticeably thick. It struck me then that the swirling misty vague paintings of his later years are exactly how the world looks if you are very short sighted.

Mike Leigh’s wonderful film, Mr Turner, offers another explanation: a sort of rage at the canvas. In one wonderful scene at the Royal Academy, Turner is putting the finishing touches to one of his pictures. He spits at the canvas, swipes it violently with hand and handkerchief, stabs at it with a brush laden with dense white paint. Painting is no genteel art, but an epic battle as harsh and unforgiving as any of the raging storms he portrays.

Interestingly, as the scene ends the camera slowly pans down the densely textured canvas, stabbed and smeared with thick white, and suddenly we are panning down a scree slope that, for a moment, seems to be part of the painting. Then, after that brief indecision between what is rendered and what is real, we see Turner pacing restlessly about a valley in the Lake District, turning from rugged cliff to dark lake. Instantly, and without ever being made explicit, the link is suggested with the Romantic notion of the sublime, awe in the face of the wild, landscapes, seascapes, stormscapes that test the observer as much as much in life as they do in the paintings.

Mr Turner is full of such moments. It is the most visually ravishing film I have seen for a long time, with an awareness of the play of light, of the quality of the scenery, that flirts with the obvious statement and yet somehow always draws back. When we see the splendidly realised moment when the Fighting Temeraire is drawn by a tug towards its grave (CGI, I presume, but excellently done), Turner and some fellow painters are in a small boat bathed in golden afternoon sunlight. ‘That would make a good subject for you, Turner,’ one of them says. ‘Would it?’ Turner grunts, unconvinced. It is an inevitable biopic moment, rescued by Timothy Spall’s tone.

Another such archetypal biopic moment comes at the first of the Royal Academy Exhibitions that we see. In the middle of one crowded wall there is a Turner seascape. When Turner goes up to examine his picture he turns to the man working on the much larger canvas hung beside it. ‘Constable,’ says Turner; ‘Turner,’ John Constable replies, equally frostily, then returns to working on some vivid red figures in the bottom foreground of his picture. Some moments later, Turner marches into the room and daubs a vivid red streak upon his own seascape. The Academicians gather round, abuzz with wonder: why should he do that, why should he spoil his own picture that way. But Constable instantly sees the echo between Turner’s red streak and the red figures he has been painstakingly adding to his own picture, recognises it as an insult and storms out. Only then does Turner return, gouges his thumbnail into the red to give it shape, wipes part of it away with his handkerchief, and lo the red daub has become a buoy that is exactly the focal point the picture needed. There is so much more conveyed in this scene than the usual biopic exchange: Turner meet Constable.

Part of the strength of it, of course, lies in the central performance by Timothy Spall, who has never been better. Much has been said about his grunts, but what is missing from the commentary is how expressive they are; full of meaning, but also full of insight into the character of Turner. But it is not just the grunting. In the scene where his first mistress, Sarah Danby (Ruth Sheen), berates him for not even attending the funeral of his own daughter, we see Turner only from the back. But the clasping and unclasping hands, the slump of the shoulders, the hang of the head, tell us as much about his emotions at this moment as if we had been looking him full in the face, perhaps more.

But the quality of Spall’s acting is not seen in isolation. Hannah Danby (Dorothy Atkinson), Sarah Danby’s niece who serves as Turner’s housekeeper and occasional mistress, is a haunting figure, her face growing progressively red and flaky with psoriasis, her shoulders perpetually slumped. But the look in her eyes whenever she watches Turner, the unrequited adoration, is absolutely heartbreaking. Contrast this with the no-nonsense good humour, the tolerance, of Sophia Booth (Marion Bailey), the Margate landlady who becomes his common law wife and in whose bed he dies. We see so clearly how she is able to capture and hold Turner at the end.

After Spall, the women are easily the most interesting characters in this film (there’s a wonderful little cameo by Lesley Manville as Mary Somerville showing Turner and his father an intriguing little scientific experiment). Nevertheless, there are some strong male performances here too. Perhaps the best is Martin Savage as the luckless Benjamin Haydon, an artist convinced of his own greatness but perennially shunned by the artistic establishment. Early in the film, Turner grumpily loans Haydon £50, and later Haydon tries to repay £10 towards the debt, but Turner rejects the money and airily cancels the whole debt, which Haydon manages to interpret as a further insult. Oddly the film is silent on Haydon’s farcical suicide, which occurred five years before Turner’s own death. Haydon had hired a room at the Egyptian Halls to display paintings that he felt would finally establish his reputation, but the show was far outsold by a performance by General Tom Thumb. With debts mounting astronomically, he tried to shoot himself, failed, and ended up cutting his own throat with a knife.

Other fine performances include David Horovitch as the doctor who tends Turner through his final illness, Paul Jesson as Turner’s father and devoted assistant, and there is a lovely little cameo by Karl Johnson as John Booth, Sophia’s husband.

But in all, with this superb ensemble going on around him, it is still Timothy Spall who holds the eye. Rough, grumpy, insensitive, yet with moments of rare sweetness as when he sings, very badly, a Purcell song on a visit to a stately home or as he declaims verse to Sophia while painting; he is not an easy man to like but clearly a very easy man to love. And there is a loneliness, too: he is often placed as a small figure in a big landscape, alone in a Dutch field, on a deserted Margate beach, on cliff tops, in the Lake District, watching a newfangled train pass by, shrouded in steam. When his father dies, he can only express his grief while trying to sketch a prostitute. His fame means he moves in high circles, but never seems at ease there. In a recital at a country house he is in a corner sketching the rest of the guests. On a visit to John Ruskin’s family home he sits silent through an hilariously excruciating conversation about gooseberries, but when Ruskin ventures a controversial opinion about the paintings of Claude, Turner responds by asking if he prefers beef pie or veal pie (in those circles, it is possible he had never tried either).

And in the end he is a tragic figure. After his father dies, we see his beautiful home slowly disintegrate around him. When he sees the first Pre-Raphaelite paintings, which look so cartoonish and garish compared to his own work, he bursts out laughing (a reaction I sympathise with, I have never liked the Pre-Raphaelites); but we know that fashion is changing. Then the young Queen Victoria describes his paintings as a yellow daub, and suddenly critical opinion swings against him, and he sees his work ridiculed on the music hall stage. Yet he cannot stop feverishly sketching, even rising from his deathbed to sketch the body of a young woman thrown up by the Thames outside the Chelsea home he shares with Sophia.

And for all that, for the performances of sustained brilliance, for the camera work that is consistently gorgeous, for the sense that here we know Turner and his world, still it is impossible to say why this is such a good film. Too many things stand out, and yet it is the totality of the film rather than any individual feature that makes it work. It is just a good film.

And we never do see Turner wearing those spectacles I saw at the Tate that time.