Brothers from left to right: Henry Forbes (b. 1882) and Gerrit Forbes (1880-ca. 1965)    

Notes: 

Image taken from Dovercards, however documentation and dating from The Smithsonian Catalogue of Works    

Bibilography:

Ormond, Richard and Elaine Kilmurray, "John Singer Sargent: complete paintings;  volume 1, The early portraits," New Haven, CT: Yale University Press, 1998, no. 196.

McKibbin, David, "Sargent's Boston," Boston: Museum of Fine Arts, 1956.

Illustration: 

Ormond, Richard and Elaine Kilmurray, "John Singer Sargent: complete paintings; volume 1, The early portraits," New Haven, CT: Yale University Press, 1998, pg. 201.