Well not withstanding your "bra designer" street cred when you came out with that statement that 28DD = "bee stings" you lost it with me.
I could name any number of women, models porn stars or other "**28**" that we would both know that are either 30DD's or 32DD's both implanted and natural (or so they say) plus having had some "hands on experience" with both sizes and both types over the years and they were handfuls, BIG handfuls,bury your face in them handfuls and no one in their right mind would characterize them as "bee stings" and while their might have been a SLIGHT difference in apparent size between the 32DD and the 2 inch smaller 30DD and to me the 30DD more often than not looked bigger, at least a little but even if they did look a little smaller the difference was not that much so the idea that dropping 2 inches from 30DD which were pretty good sized handfuls down to a 28DD and all the sudden you get "bee stings" sorry but I am not going to buy that.
In case you have not figured it out when I say what I say I am employing the "eye test" and "how they look" and it is more the volume of what is in that bra and how it looks compared to a like volume, it may be that the actual volume of breast tissue on a 48DD woman is more maybe twice that of what is on a 30DD but the woman with the 30DD's looks bigger, more often than not a LOT bigger.
It may be that if you strictly apply the number to this BS UK sizing system you get what you get but I contend that the UK system was "invented" back 10 or so years ago because before then I had never heard of it and that first generation of UK and EU women, LDM, Lorna Morgan, Chloe V and a few others were not measured by it. So now all these somewhat busty women can "sound bigger" "look at me I am a H cup" in some cases a LOT bigger than they really are or what most of us think of, DD's are Christy Canyon, FF's are an early Lorna Morgan or Chloe V H's are Sarena Lee, HH' LDM and so on, and this "sounding bigger was the entire reason it was "invented" it was NOT as some contend about "accuracy"