Artists seldom painted the interior of their studio until the nineteenth century, and it was unheard of in the Renaissance. So when you’re offered a glimpse into that of Sandro Botticelli in the 1480s you’d be justifiably suspicious, particularly when it wasn’t painted until 1922, over half a millennium later.

Nevertheless, almost exactly eleven years ago, on the fifth of November 2014, a remarkable painting claiming to depict Botticelli’s studio at that time was auctioned in New York. Captured on its canvas were the faces of those long dead, those of the artist and members of the Medici family.

The painting’s title reveals its key figures: Botticelli’s studio: The first visit of Simonetta presented by Giulio and Lorenzo de Medici (1922). The artist stands at the left in front of an exquisite tondo he is working on. Bowing to him at the centre is Giuliano de’ Medici, who is accompanied by Simonetta Vespucci, wearing the green dress. Behind her is Lorenzo de’ Medici, also known as Lorenzo the Magnificent, and behind him are Giovanna Tornabuoni and her attendants. The view through the window is of the Palazzo Vecchio in the centre of Florence.

Painted by the British artist Eleanor Fortescue-Brickdale, those figures weren’t based on models or imagination, but on contemporary sources.

Giovanna Tornabuoni comes from a detail of Domenico Ghirlandaio’s painting The Visitation (c 1488) in the Tornabuoni Chapel of the Church of Santa Maria Novella in Florence. Giovanna was born as Giovanna degli Albizzi in 1468, married Lorenzo Tornabuoni in 1486 when she was about eighteen, and died in childbirth two years later in 1488. She is here accompanied by her maid and nurse.

Lorenzo de’ Medici (1449-1492) hails from Girolamo Macchietti’s undated portrait of Lorenzo the Magnificent. Lorenzo was born in 1449 into the banking family, the grandson of Cosimo de’ Medici, at the time one of the wealthiest and most powerful people in Europe. Lorenzo was groomed for power, and became de facto ruler of the Florentine Republic when his father died in 1469.

He survived an attempted assassination in the Cathedral of Santa Maria del Fiore on Easter Sunday 1478, in which his brother Giuliano was stabbed to death. This led to his excommunication, and invasion by forces of the King of Naples. He resolved that, and died in 1492, when he was forty-three.

Botticelli also painted this Portrait of Giuliano de’ Medici in about 1475. Giuliano was born in 1453, younger brother and co-ruler of the Florentine Republic with Lorenzo. He was brutally murdered in that attack in the cathedral on Easter Sunday 1478, dying at the age of twenty-five. Although he never married, an illegitimate son of his became Pope Clement VII.

The painting shown in progress is Botticelli’s Madonna of the Magnificat, thought to have been completed in 1483. It shows the Virgin Mary being crowned by a pair of angels, writing down the start of the Magnificat in a book, and holding a pomegranate in her left hand. It has also been interpreted as a family portrait of the de’ Medicis, in which the Virgin is Lucrezia Tornabuoni, the mother of Lorenzo and Giuliano de’ Medici, who are the angels. I believe that Lucrezia was one of Giovanna Tornabuoni’s aunts by marriage.

The source of the likeness of Botticelli is more of a problem, as he isn’t known to have painted a formal self-portrait. It’s generally believed, though, that he revealed himself in cameo in this detail from his The Adoration of the Magi from about 1475.

It’s also thought that Filippino Lippi included his portrait in this section he painted in 1483-84 of Massaccio’s incomplete fresco in the Cappella Brancacci, Santa Maria del Carmine, Florence, in Disputation with Simon Magus and Crucifixion of St Peter.

But of all the figures shown in this painting, Simonetta Vespucci is the most fascinating. She was born Simonetta Cattaneo in 1453, and when she was only fifteen or sixteen, she married Marco Vespucci, cousin of Amerigo Vespucci, the first to demonstrate that the New World of the West Indies and Brazil wasn’t part of Asia.

Once married, she lived with her husband in Florence, where she was a great favourite at the court of the de’ Medicis. Giuliano de’ Medici entered a jousting tournament in 1475 bearing a banner with an image of Simonetta as Pallas Athene, painted by Botticelli. She had the reputation of being the most beautiful woman in the whole of northern Italy, but that beauty was fleeting as she died of tuberculosis in 1476, when she was only twenty-two.

Many paintings have been claimed to be portraits of her, but perhaps the most credible is Piero di Cosimo’s Portrait of Simonetta Vespucci from 1490.

Several of Botticelli’s works have been claimed to feature figures for which Simonetta modelled, even the naked Venus in his famous The Birth of Venus (1484-86). The least unlikely might be his Idealized Portrait of a Lady, also known as Portrait of Simonetta Vespucci as Nymph, thought to have been painted in 1480, four years after her death. Such portraits were commonly not true to life, but idealisations intended to flatter rather than identify, so we will never know if she was its subject.

Inevitably, time in Botticelli’s studio is slightly out of joint. The figures might have been able to gather together in this way in about 1475, before the deaths of Simonetta and Giuliano de’ Medici, but that is well before Botticelli might have painted Madonna of the Magnificat, and when Giovanna Tornabuoni was still a child.

This remarkable painting was the second of its kind by Eleanor Fortescue-Brickdale.

Two years previously, in 1920, she had painted The Forerunner, showing Leonardo da Vinci trying to convince the Milanese court of his idea for flying machines. Notable figures included here are (from the left) Savonarola (from Fra Bartolomeo’s portrait), Beatrice d’Este (Duchess of Milan), Cecilia Gallerani, Elisabetta Gonzaga, Leonardo da Vinci, and Ludovico Sforza (Duke of Milan, and Leonardo’s patron).

Eleanor Fortescue-Brickdale sold The Forerunner to Lord Leverhulme, and it is now on view in the Lady Lever Art Gallery. She was subsequently commissioned to paint Botticelli’s Studio in 1922 for Montague Rendell. That was shown at the Royal Academy later that year, and has been in a succession of private collections since.