Percy Grainger was an Australian-born composer, arranger and pianist. In the course of a long and innovative career he played a prominent role in the revival of interest in British folk music in the early years of the century.
The large cap was a standard day hat in this era. You see it worn less in modern films and shows representing the I think because the size can look vaguely silly to modern eyes. But see prince of wales picture in this board, it was a serious hat.