Claud Walsingham Popple is probably based on John Singer Sargent rather than James MacNeil Whistler, as I said in class. Sargent was a successful “society painter” who first gained attention with the “scandalous” work Portrait of Madame X.
A prolific artist, Sargent prospered to such a degree he was able to pick and choose his subjects. Elite figures of high society clamored for him to “do” them. Here is a sampling of such portraits taken from artstor.org– a very valuable image database that you should consult.