
Having been on a breed club committee, I can answer this.
Breed club committees decide what criteria, or qualifications are required for each of the lists. C list judges are gaining experience, and collecting, numbers(of dogs) to progress to the B list. The numbers required are part of the decision that the committees make. Usually there is a stipulation about appointments having a good geographical spread. A list judges have been passed by the Kennel Club to award CCs in a given breed. Then there are A1 and A2 lists.A1 have awarded CCs in the breed in the past and A2 are passed by the KC but might not yet have actually awarded the CCs. A new Judge can apply to the breed club to be entered onto there C list providing information such as, years of experience in the breed, seminars attended, show ring success in terms of dogs owned or bred that have acheived stud book numbers. You do not HAVE to be on a breed club judging list to start a judging career, the breed clubs acceptance of a person onto their lists is their approval of a judge.
Hope this helps you to get a handle on this complicated subject, no doubt others will be able to add a few more details.
Dawn R.