What does "rides a hobby-horse" mean in the following sentence?

Hollis Demasters: It means that Churchill is a pretender.A hobby horse is a toy horse.If a person is riding a hobby horse, he is not riding a real horse. He is only pretending to ride a horse.I wonder who said that. The opinion of Churchill in America is that he was a great British leader.Peace be with you....Show more

Solomon Belback: Sounds like Churchill is waisting time.