zeallady

I read this childrens book 20 years ago about a deaf boy who lives on dartmoor. He gets mixed up in a chase across the moor to find a dragon thats been hidden in the stones of a quarry - this is what the cover of the book shows - the dragon half living half stone. Its magic fiction - as far as I can remember there are hellhound type things that chase him andd this magician type bloke that is looking for the dragon. I'd love to find this, please help if you know the author or title.