Tailors love the 16th-century Italian artist Giovanni Battista Moroni, as the Royal Academy – situated halfway between the bespoke shirt and made-to-measure pinstripe superhighways of Jermyn Street and Savile Row – has discovered.The academy is about to launch the first major exhibition in the UK of the painter whose best known work shows a tailor in action, gathering together rare loans including his late religious paintings and altarpieces that have never left Italy before, and one portrait only identified as his work last year by the curators of this show.The tailor, who has been in the Natonal Gallery collection since the 19th century, is the earliest known portrait of a craftsman engaged in manual labour, pausing to look enigmatically at the viewer, shears in hand and about to tackle a length of costly black fabric already marked up in chalk before him.It’s not surprising that tailors love it: it shows a confident and immensly dignified man doing a skilled and well-paid job, rather than one who has done well enough to pay an artist to immortalise him as an aspirant aristocrat. Moroni’s tailor obviously has done very well, wearing a gentleman’s sword belt, a gold ring, and quietly costly clothing including frills of lace at his wrists and throat.This was unique, curator Arturo Galansino said: “It had never been done before. The tailor is one of the most revolutionary portraits in all of art history.”The painting was already well known by the 17th century in Venice, the luxury capital of Europe. Moroni was acclaimed, somewhat grudgingly, for the striking realism of his portraits.One anecdote has a Venetian official based in Bergamo coming to Venice to try and commission a portrait from the most famous painter of the day, Titian. The master tells him to go back to Bergamo, where there is the best portrait painter famous for his naturalism.This, Galansino says, was a double-edged compliment: naturalistic portraiture – although Moroni’s work is believed to have heavily influenced the young genius Caravaggio – was the least regarded rung on the artistic ladder, far inferior to bombastic history paintings or symbolism overloaded allegories.Isotta Brembati, c.1555, by Giovanni Battista Moroni Isotta Brembati, c.1555, by Giovanni Battista Moroni. Photograph: Fondazione Museo di Palazzo Moroni - Lucretia Moroni Collection, BergamoHowever, Galansino points out that many of his other portraits are fashion and textile-history treasures, showing the quality of fabrics and the details of the construction of garments in pristine detail, as well as recording fashions which changed so fast that the gowns of two magnificently dressed young women changed completely inside five years. Isotta Brembati, coming on loan from a museum in Bergamo, where Moroni lived and worked for many years, was painted in about 1555. She is wearing a green and gold velvet gown, with the low-cut neckline grazing her nipples. Five years later another portrait shows an equally expensively dressed woman in pink silk brocade buttoned up to the throat, with a high lace-edged ruff.Many of Moroni’s subjects, though magnificently and fashionably dressed – particularly men in the sobre blacks that were actually the most expensive colours because they took so much costly dye – have rough outdoor complexions, far from the waxy smoothness of many Venetian portraits.“There is no doubt that Moroni is the greatest at showing you the person he is standing in front of, and not just the outer appearance but the inner man,” Galansino said. “But people would not have thought this was his most important work, and he would not have thought so himself.”Relatively little is known about the artist, despite the curators’ attempts to draw together every scrap of recorded information. He was born in Albino in the province of Bergamo, found local civil and religious patrons, and is not recorded as travelling outside Lombardy though he is assumed to have gone to Venice. He died relatively young, in his 50s, and is said to have worked himself to death, completing all his commissions alone without studio assistants or pupils.It was Moroni’s bad luck (and this, curators believe, explains why he isn’t a household name today) that his contemporary Giorgio Vasari never came to Bergamo and so didn’t know his work. Vasari’s pioneering work, Lives of the Most Excellent Painters, Sculptors and Architects, which combined descriptions and criticisms of artwork with gossipy anecdotes about their makers, misses out Moroni completely.