
To be clear, the painting was done from life, not from the photo, but both date from the mid 1890s.
Patmore was so impressed with Sargent’s interpretation of him that he wrote: “He seems to me to be the greatest, not only of living English portrait painters, but of all English portrait painters; and to be thus invited to sit to him for my picture is among the most signal honours I have ever received.”
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From the book John Singer Sargent by Richard Ormond, 1970, figure 21 and 22. Thanks, Barry!
ADDENDUM: Don't miss the fascinating string of comments on the subject of sight-size practice.