Kathleen Costello Beer (1927 - 2001) was an artist and author. She was born in Baltimore, and competed successfully in top equestrian events. She taught art, and painted. She founded the Beresford Gallery, and wrote two books, one of which, Bumble and Me, is a horse story.
Finding the book:can be tricky, but the Beresford Gallery appear to have reprinted it.
Thanks to Lisa Catz for the photographs and summaries
Bumble and Me
D Van Nostrand Company, Inc, 1968, 63 pp, illus Judith Gellert
Beresford Gallery, unknown
Photos and limited text tell the story of a young girl and her constant companion, her pony Bumble.
Elizabeth takes care of Bumble herself, brushing him, picking out his feet, and feeding him. They share many happy times, including visiting the other horses, swimming in the stream, and going for drives with the pony cart. Bumble is a playful and patient pony, but not without a stubborn streak.