The sitter may be the daughter of the Florentine Matteo Soffaroni. The portrait appears to date from early in Bronzino's career when he was strongly influenced by his master Pontormo. The direct gaze, simple pose and precision of technique are typical of Bronzino's portraits.

There has always been some uncertainty about the authorship of this magnificent Portrait of a Lady in Green. The sixteenth-century inscription of 'Di Mano di Rafaelo da Vrbin' (by the hand of Raphael of Urbino) on the back of the painting and early inventories attributed it to Raphael; subsequent inventories cite Andrea del Sarto and Sebastiano del Piombo; twentieth-century opinion has attributed the portrait to Pontormo, or to artists in Emilia or Lombardy, such as Girolamo da Carpi. Scholars have used the comparison with Bronzino's Lady in Red of c.1532-5 (Städelsches Kunstinstitut, Frankfurt) to suggest that this work is too informal in pose, too simple in setting and too imprecisely finished to be by the same artist. In fact the simplicity of the setting is very similar to that in Bronzino's portrait Lorenzo Lenzi (Castello Sforzesco, Milan), which has also been ascribed to Pontormo. Both can be placed early in Bronzino's career in the early 1530s, when he was strongly influenced by the older artist. The direct gaze and the deceptively simple pose of the figure are also typical of Bronzino's portraits. The detail of the treatment is directly comparable to The Lady in Red: the turn of the head, the reflected light in the shadows of the face, the very slightly parted lips, the depiction of the rings worn on rounded hands. Above all, the precision of Bronzino's technique is evident here, memorably summed up in Hazlitt's description of this work: 'The portrait of a lady with green and white purfled sleeves (like the leaves and flower of the water-lily, and as clear!) is admirable.'

This portrait has been connected with Bronzino's period working within the Duchy of Urbino. He is recorded at Pesaro from the end of 1530 until 1532, and Vasari wrote that while he worked for the Duke of Urbino, Francesco Maria della Rovere, 'he painted the portrait of a daughter of Matteo Sofferoni'. It has been suggested that this portrait might be Sofferoni's daughter, and that it would be at the Court of Urbino rather than in Florence that a portrait by Bronzino could be mistaken for one by Raphael, hence the inscription on the back of the painting. The portrait is not recorded in Florentine inventories and it was from a northern court that Charles I acquired the painting in 1629-32.

Sofferoni was a customs official in Florence and a member of the same literary and artistic circle as Pontormo and Bronzino. Bronzino was an especially close friend of Matteo's sister's husband, the swordmaker Tofano Allori. When Tofano Allori died in 1541 Bronzino assumed financial responsibility for his family, moved into the Allori house and trained his son, Alessandro, as a painter. Matteo Sofferoni was a merchant rather than a nobleman; this fact and his friendship with Bronzino might explain the greater sense of intimacy and informality in this portrait compared with the slightly later and almost certainly patrician Lady in Red.

Costume historians are divided over whether the sitter's clothes are northern Italian or Florentine. Two elements are perplexing: one would expect a headdress of this date to be much larger, matching the sleeves in effect, and the sleeves to be gathered tightly at the elbows, rather than loosely as here. If the sitter is Matteo's daughter, it is less likely that she accompanied him to Urbino and was painted in north Italian fashion, and more likely that she was painted in Florentine dress in Florence either before or after Bronzino's visit to the Duchy.

Recent technical analysis lends more credence to the attribution to Bronzino. X-radiography has revealed particular signs of damage along the top and bottom edges of the panel, matched on other Bronzino panels. Although many preparatory drawings by Bronzino may have been lost, it seems that he preferred to paint a composition to a fairly advanced state and then sometimes make radical changes. X-radiography of the present painting further shows that Bronzino mapped out an earlier face to the right and on a more vertical axis than the final version. The chin of the sitter is aligned with this earlier position of the head, contributing to the fascinating distortion of the portrait. The other adjustments are also typical of the small changes that Bronzino liked to make.

Catalogue entry adapted from The Art of Italy in the Royal Collection: Renaissance and Baroque, London, 2007