Looking at my BSAC qualification record book, on the Advanced Diver page. It says:-There are other agencies who use the more traditional meaning of "advanced" -- a much higher standard. BSAC is well beyond DiveMaster for example, maybe NAUI too.
(Equivalent to CMAS Three Star Diver)
Formerly known as BSAC Second Class Diver
This is far more descriptive as it’s obviously above third class and below first class.