Johan Zoffany: The lovable artist who ate a sailor English milordi on what would be called the Grand Tour invariably wanted to take back a portrait and a view, creating a busy and superior clientele for portraitists like Pompeo Batoni or the German expatriate Raphael Mengs, or Venetian painters like Canaletto. The sense of the English as a lively country of independent-minded artists and rich patrons must have stuck in Zoffany's mind. Though there is no evidence that Zoffany had direct contact with English patrons or artists at this time; after a decade shuttling between Italy and Germany, he moved to London in 1760, and, apart from occasional excursions, remained there until his death 50 years later. Zoffany moved to England with his eye on the main chance, as many great artists before and since have done. In that happy age before state funding and the filling out of outreach compliance forms, a painter relied upon attracting patrons who liked his art enough to shell out for it. They either paid up, and made a Reynolds or a Gainsborough rich; or they walked away, forcing a Richard Wilson or a James Barry into poverty. Zoffany's age was trying to codify artistic manners, under the aegis of Joshua Reynolds's Royal Academy, and his commitment to a sort of hierarchy of painting where "History Painting" sat at the top, and mere painters of flowers and farmyard animals at the bottom. It was also, however, an age where some notable eccentrics found a place. There are great painters of bandits, like John Hamilton Mortimer, of eruptions and scientific experiments, like Joseph Wright; there are painters whose best work is of a horse standing in a field, like the sublime Stubbs, or of pigs in a yard, like George Morland; there are mad fantasists like Fuseli or Blake; there are mythologisers like James Barry who see nothing strange in depicting musicologists swimming in the Thames in full wig and coat, pushing Neptune along in a boat; there are portraitists who openly mock their sitters by putting them in the most absurd fancy dress they can think of, like George Knapton. You can find many unexpected things in 18th-century art, and one of the most lovable is Zoffany. Zoffany's best art all has a silvery clarity, and a love of documentary detail which his patrons adored. He must be the greatest painter of English royalty between Van Dyck and Winterhalter. In his royal paintings, such as the wonderful Queen Charlotte With Her Two Eldest Sons, royalty appears with the necessary spectacle, and even with a whimsical appearance, but also off-duty, relaxed. Other painters of the period, like Gainsborough, rendered royalty as private individuals; Zoffany's royals have a curious quality, suggesting that they have wandered off from stiffer, stately duties and have flung themselves down without changing their clothes to be alone with each other and the painter. They have, unexpectedly, a connection with Zoffany's large and innovative series of portraits of actors in their best and most memorable roles. At any rate, these pleased the royal family, who commissioned some bolder works from Zoffany. The beautifully exact John Cuff and His Assistant shows an old lens-grinder in his workshop, every tool and knot of wood depicted with hallucinatory precision, and an old man enjoying his own expertise at the centre of it. Two grander works are also in the exhibition, a group portrait of the Royal Academicians at a life class - the two female academicians had to be depicted through their portraits hanging on the wall, rather than gazing at a naked man. There is also the great Tribuna of the Uffizi, an extraordinary tour de force showing a crowd in an art gallery, allowing Zoffany to show off his supreme skills of imitation and trompe l'oeil. It may have been an eye on the main chance, too, which took Zoffany off to India in 1783. Certainly his contemporaries thought so, noting with amazement that within two years he had sent home the huge sum of £36,000 with commissions to the value of £30,000 to follow. There may have been, too, a sense that the spectacular full-length portraits and broad, theatrical painting styles of Reynolds and Romney were commanding fashion in London, rather than Zoffany's exact approach. Nevertheless, Zoffany genuinely took an interest in Indian and Anglo-Indian society. We hear of him, much later, back in London, discovering that the Romany language has vocabulary in common with Bengali. He was an active member, in Calcutta, of Sir William Jones's Asiatic Society, founded in 1784 to inquire into the languages and culture of India. There is a sense of letting the hair down about some of Zoffany's Indian paintings. The masterpiece Colonel Mordaunt's Cock Match depicts the meeting between cultures at its most rumbustious, complete with extremely vulgar allusions to the principal figures" sexual prowess. The bizarre Last Supper may actually be a joke: it depicts 13 members of fashionable Anglo-Indian society as Christ and his disciples, including a noted transvestite magistrate as St John. "The painting is not an exact replica of Leonardo's masterpiece," one modern-day Indian scholar notes. Zoffany may be the most worldly painter in English history, fascinated by any new phenomenon. He was constantly willing to get on a boat or a camel or just set off on foot, and endure vast discomfort, no doubt, for the sake of something interesting. He produced not just images of the whole range of English society, but the first authoritative glimpse of the English encounter with India, and others beside. As early as 1794, he was exhibiting a modern history painting of the behaviour of the revolutionary mob in Paris - almost certainly the first artist, apart from the print satirists, to produce any serious response. Zoffany has suffered, in the past, from being seen as a foreign artist, and perhaps too varied in his subjects - nothing much unites his interests apart from the unmistakable, silvery, precise in which they are surface they are rendered. But other great painters of the English Enlightenment have been returned to view - Reynolds, Stubbs, Fuseli, Wright. Is this the moment for this fascinating painter, part-time cannibal, full-time observer of his society, to come back to his rightful place? "Johan Zoffany - Society Observed" is at the Royal Academy of Arts, London W1, March 10 - June 10.