
Ask the previous owner or the breeder to get you the papers. the old owner may have lost them, but in this situation the Kennel Club will issue new ones once they know for sure that ownership changed. the breeeder can then pass the documents onto you for you to transfer the ownership.
Legally the dog is yours, as you have bought it, it just isn't registered in your name, so you wouldn't be able to show it or breed from it even if it has no endorsements on it's papers.