The Kennel Club (KC) issue quarterly Breed Record Supplements (BRS) that include the registrations of all the puppies registered during that quarter (along with change of name, imports, exports, tranfers, stud book numbers: CC, JW and ShCM achievers and any corrections to previous issues. In the back they have the hip, eye and other relevant tests for different breeds that there are schemes for.
2004 = AE1 / AE2 / AE3 / AE4
This year will be AF1/2/3/5
Prior to AA, AB, AC, AD was A01, A02, ........... Z03, Z04
Prior to that they just used the year and month - the BRS went from monthly to quarterly between K and J