Painting, oil painting

Oil painting on canvas of the head and torso of a seated man. He has a slightly receding hairline, with dark coloured hair. He is wearing a dark clothing, but has a white shirt visible. His right hand is on the arm of his chair and his left in his lap. To his left sits a pair of glasses resting on an open book. There is a smudged black ink stamp on the reverse of the canvas that says, ‘William Forward, Artists Colourman, No. 30[?] Piccadilly’.
William Forward worked as an artists' colourman at 30 Piccadilly from 1840-1847, providing a date range for this canvas, although the painting could of course have been executed at a later date.