Who was the artist who drew this lovely portrait of Joseph Dalton Hooker aged 38?

George Richmond RA (28 March 1809 – 19 March 1896) was an English painter and portraitist. In his youth he was a member of The Ancients, a group of followers of William Blake. Later in life he established a career as a portrait painter, which included painting the portraits of the British gentry, nobility and royalty.He was the son of Thomas Richmond, miniature-painter, and was the father of the painter William Blake Richmond as well as the grandfather of the naval historian, Admiral Sir Herbert Richmond.
​His success as a portrait-painter was due as much to his power of drawing out the best from his sitter in conversation as to skill in delineation. Being a very skilful and rapid draughtsman, he was able, while putting himself into sympathy with his sitter, to report the happiest moment and fleeting changes of expression, and to get out of his subject more than at first sight appeared to be there. His ideal of portraiture was ‘the truth lovingly told;’ and he never consciously flattered. He was also a most industrious and clever sketcher from nature, and he produced (for his own pleasure and instruction) hundreds of drawings in pencil and watercolour, many of great beauty, of figure and landscape.