The ambiguous nature of the inscription has led to much confusion. Both Andrea Rose and Angela Thirlwell have published the drawing in recent years as the only known example of a self-portrait by William Michael Rossetti. In other words, they read 'WM Rossetti' as a signature, albeit 'not in his typical hand', rather than an identification of the sitter. But there are compelling reasons for believing that the drawing is in fact a portrait of William Michael by his brother Dante Gabriel.
First and foremost, the words 'By Gabriel' are written on the back of the drawing, almost certainly by William Michael himself. Perhaps he realised that the inscription on the drawing was equivocal, and was attempting to forestall confusion.
An attribution to Dante Gabriel is also supported by the stylistic evidence. Many examples of William Michael's portrait drawings survive, including the two in this sale (lots 11 and 12) and others illustrated in Angela Thirlwell's book (pp. 108-115). They have a consistent style which is not found in the present drawing. On the other hand, the drawing is fully compatible with the work of Dante Gabriel at this date (1846). Indeed another drawing in this sale, in which he represents the same sitter at about the same date (lot 1), offers a very close stylistic comparison.
It is true that when the latter drawing was included in Dante Gabriel's memorial exhibition at the Burlington Fine Arts Club in 1883, William Michael described it in the Art Journal as 'the only portrait, of a tolerably accurate and detailed kind, that I remember his ever taking of me'. But the writer goes on to say that 'there [were], however, one or two slight sketches besides'. One of these must by the present drawing.