Mike Leigh doesn't often venture into the past but when he does - with Vera Drake, Topsy Turvy and now Mr Turner - he produces some of his very best films.

One wonders whether it's a coincidence that two of these are about artists, the composers Gilbert and Sullivan, and the painter JMW Turner. Could his best work also be his most personal?

It's tempting to go a step further, and see a correlation between the gruff and single-minded Turner and Leigh himself, whose public persona is famously bullish. Timothy Spall, with whom Leigh has often worked, may well have offered us a sneaky impersonation. Whether that's true or not, Mr Turner is a fascinating, wonderfully evocative and often highly entertaining portrait of one of Britain's greatest painters, charting the last 25 years of his life, a warts-and-all account of a complicated, not always likeable man, but a brilliant artist.

The film doesn't get embroiled in creative inspiration, an understanding of what made the man tick, but is concerned with the day-to-day of the painter's life - from shopping for pigments and drawing the landscapes that will be the subject of his paintings, to investigating new scientific theories about colour and light, meeting with potential clients and wealthy patrons, romancing and dealing with ill health.

We join Turner at the height of his powers and fame, a favourite of the Royal Academy and successful enough to be living in comfort with his ageing father (Paul Jesson), a former barber and wig maker who now spends his retirement as his son's dedicated assistant.

As Turner returns from a trip to Holland, we immediately see two sides of the artist. When his loyal but poorly treated servant Hannah (Dorothy Atkinson) inquires of his journey home, he growls out one word - "execrable" - while thrusting his dirty linen into her arms; but when joined by his father, he gaily reports of having "another gander at the Rembrandt", the two men affectionately rubbing cheeks.

His moods are not easily second-guessed. He loves his father, but has nothing but disdain for his former mistress and disinterest in their two daughters; some fellow painters he likes or admires, others not - a terrific sequence at the Academy reveals the full range of responses to his colleagues, as well as his maverick presence amongst them. He's a different man to all, his sympathy to be gauged by the degree to which, literally, he moves his mouth.

Spall has come up with a remarkable, richly expressive vocabulary of growls and grunts, to designate any number of feelings, united by reticence. The impression is not of inherent ill temper, more a forceful focus on his work that makes human relations largely an inconvenience.

In contrast to the twee stuffiness of so much period fare, Leigh's depiction of the 1800s is meticulously detailed and refreshingly real; we feel a genuine sense of how these interiors may have been occupied. In capturing the natural locations favoured by the artist, cinematographer Dick Pope frequently captures the essence of the paintings themselves, with their supernatural feel for colour and light.

Some may regret the absence of traditional biopic back story - what led this man to painting and to such a mighty sense of vocation (at one point he ties himself to the mast of a ship), what instilled his passion for the sea? But what would be damaging omissions in a lesser film, are here outweighed by considerable pleasure and - fittingly, given the paintings before us - a more abstract insight into an artist's mind.