Mystery Man in Church

Sketch of a man in church, by Giovanni Boldini (1842-1931)

Boldini painted a man near him in church. Who is that man?

Boldini Portrait of Sem (Georges Gourçat)

According to Christies, "it could represent the caricaturist Georges Gourçat, known as Sem (1863-1934), who was a good friend of Boldini."