The Italian Giovanni Boldini (1842-1931) was one of the and most successful portraitist of the Belle Epoque and one of his best known paintings is the "Marchesa Luisa Casati, with a Greyhound" (1908).
And because John Galliano is a great admirer of Boldini and especially of this painting he ordered that the campaign for his new perfume should be a reference to the Marchesa Casati and the spirit of the Belle Epoque.