Who is Mr. Mulliner from The Most of P.G. Wodehouse and what is their importance?

Mr. Mulliner is a man whose family is filled with exemplary individuals, all excellent illustrations of some point of ideal conduct Mr. Mulliner is desiring to explain to someone at the Drones' Club. People equally enjoy and gather around to hear his stories, and listen with some impatience, depending on their circumstances, as he launches in to what are invariably long and highly details accounts of his family's adventures.