Joe and the Gladiator by Catherine Cookson

What with trouble at home between his parents and trouble with a bully at the Tyneside shipyard where he works, life is pretty bleak for fifteen-year-old Joe Darling. Then an unlikely friendship with an old rag-and-bone man, Mr. Prodhurst, leads him into the greatest challenge of his life. For Mr. Prodhurst bequeaths his peculiar-looking horse, The Gladiator, to Joe — with only enough money for a couple of weeks feed!How can Joe possibly look after the horse properly? He is determined to try. Otherwise, The Gladiator will have to be put down…A tense and absorbing tale of one boy’s courage and determination to succeed against all the odds.