i am sure someone will explain it better than me but to qualifiy a dog for its stud book number you have to look up the band the dog is in the kennel club put the breed in a certain band and it may be the 1st in your dogs breed in say limit class get there stud book number and qualifies for crufts for life some dogs can only qualifie in limit classes others in open so it all depends what breed you have and what band your dog falls into.
sorry not explained clearly but i have looked up my dogs band and it is what i thought