It is one of only two works of art definitively identifiable as a depiction of the poet; the other is the statue erected as his funeral monument in Shakespeare's home town of Stratford-upon-Avon.

Critics have generally been unimpressed by it as a work of art, although the engraving has had a few defenders, and exponents of the Shakespeare authorship question have claimed to find coded messages within it.

Later copies of the second state, with minor retouching, were also printed from the plate by Thomas Cotes in 1632, for Robert Allot's Second Folio, a new edition of the collected plays.

Edmond writes, It seems perverse to attribute the Shakespeare engraving to the obscure and unsuitably young Martin Droeshout, born in 1601, as is customary, when there is a quite well-documented artist of the same name to hand, in the person of his uncle".

On the evidence of these plates, which were made between 1635 and 1639, Schuckman attributed the portrait of Shakespeare to the younger Martin and suggested that the engraver had converted to Catholicism and emigrated to Spain in 1635, where he continued to work.

[6] Although she began her archival research hoping to prove Edmond's assertion that the elder Martin was the Shakespeare engraver, Schlueter concludes that the newly discovered evidence actually supports the younger.

[1] The engraving is praised by Shakespeare's friend Ben Jonson in his poem To the Reader printed alongside it, in which he says that it is a good likeness of the poet.

As the 19th-century artist and writer Abraham Wivell put it, It is, as I may say, the key to unlock and detect almost all the impositions that have, at various times, arrested so much of public attention.

The 19th-century scholar George Scharf argued on the basis of the inconsistencies in the lights and shadows that the original image would have been "either a limning or a crayon drawing".

Samuel Schoenbaum was equally dismissive:In the Shakespeare engraving a huge head, placed against a starched ruff, surmounts an absurdly small tunic with oversized shoulder-wings ... Light comes from several directions simultaneously: it falls on the bulbous protuberance of forehead – that "horrible hydrocephalous development", as it has been called – creates an odd crescent under the right eye and (in the second state) illuminates the edge of the hair on the right side.

The 19th-century writer James Boaden wrote that "to me the portrait exhibits an aspect of calm benevolence and tender thought, great comprehension and a kind of mixt feeling, as when melancholy yields to the suggestions of fancy".

[18] More recently, Park Honan has written that "if the portrait lacks the 'sparkle' of a witty poet, it suggests the inwardness of a writer of great intelligence, an independent man who is not insensitive to the pain of others.

"[14] In 1911, William Stone Booth published a book claiming to demonstrate that the features of the engraving were "anatomically identical" to those of Francis Bacon, proving that he wrote the works.

[22] An alternative approach has been to claim that the portrait depicts William Shakespeare, but does so in a way designed to ridicule him by making him look ugly, or to suggest that he is a mask for a hidden author.

The double line created by the gap between the modelling shadow and the jawline has been used to suggest that it is a mask, as has the shape of the doublet, which is claimed to represent both the back and front of the body.

An engraving of John Davies of Hereford shares most of these quirks for example, including the uncertain placing of the head on the body and the "same awkward difference in design between the right and left shoulders".