Martin (1737-97) had been a pupil of the portrait painter Allan Ramsay in Edinburgh at the age of sixteen. By 1762 he was in London copying Ramsay's coronation portraits of George III. He seems to have made his few mezzotints as a means of supplementing his income and perhaps establishing a reputation independent of his master. This signed and dated print is dedicated to his patron Robert Alexander, the Edinburgh banker and merchant, who had acquired the painting on which it is based.
Its subject, Louis François Roubiliac (1702-62), had moved from France and established himself as a successful sculptor in England by the 1740s. After he had completed his statue of Sir Isaac Newton (Trinity College, Cambridge), he was commissioned by David Garrick, the greatest actor of his day, to sculpt a full-length marble portrait of Shakespeare. The sculpture was finished in 1758, and set up in the 'Temple of Shakespeare' that Garrick had built in the garden of his villa at Hampton. He bequeathed the statue to The British Museum in 1779.
The painting, by Roubiliac's Swiss friend Adrien Carpentiers, is in the collection of the National Portrait Gallery. The mezzotint shows Roubiliac finishing the terracotta model on which the marble was based. His open mouth and upward-staring gaze suggest that he is in awe of the lofty genius of Shakespeare even as manifest in his own handiwork.