The historian Aubrey, who knew him, called Dobson 'the most excellent painter that England hath yet bred', and leaving aside Hilliard, who as a miniature painter is a special case, this remains the modern view. Nothing is known of Dobson until the last years of his short life, when he appears in 1642 as court painter to Charles I in exile in Oxford during the Civil War. Only about sixty paintings by Dobson are known and this one is often considered to be the best of them all. In it Dobson's style appears as completely accomplished in the new manner introduced by Van Dyck, but Dobson had evidently studied on his own account, and with profit, the great Renaissance paintings in the Royal Collection: the rich and beautiful colour scheme of brown and gold in this picture is reminiscent of Titian, and the pose is in fact taken from a Titian then in the Royal Collection, an imaginary portrait of the Roman emperor, Vespasian. This, like almost everything else about this picture, is significant: the reference links both painter and sitter to one of the most admired Italian Renaissance painters and to the world of classical culture. This latter is referred to much more explicitly by the bust of Apollo, Greek god of the arts, in the top left corner of the painting, and the classical sculptural frieze that Porter is leaning on. It depicts three figures representing, from left to right, the arts of painting, sculpture and poetry. All this is meant to tell us that Porter was a man of great intellectual accomplishment, particularly in the arts, which, in fact, he was. A leading courtier of Charles I, he knew and assisted many of the best writers of his day and played an important part in locating and acquiring works of art for the King. The sculpture being made by the central figure in the frieze is a statue of Pallas Athene, the Greek goddess of the arts and sciences, but also of war: she carries a shield and spear. This is almost certainly a reference to the war that Porter was assisting his King to fight at that time.
Although the picture emphasises Porter's intellectual accomplishment, it also presents him as an outdoor man and if not a warrior, at least a huntsman. He is in hunting costume and carries a fine wheel-lock hunting gun which takes a prominent place in the picture.
Although owing much to Van Dyck, Dobson's style is personal, with a down-to-earth quality which is characteristically British. This is particularly apparent in the painting of the face, where the puffy eyes hint at the strains of war. It is possible that the dead hare is also a reference to what was an ever present threat at that time, but the young page boy and faithful dog bring a gentler touch of pathos to the otherwise rather austere gloom of the work.
Simon Wilson, Tate Gallery: An Illustrated Companion, Tate Gallery, London, revised edition 1991, p.18