"Of course I believe that there is a sound scientific basis to what the experts have said re "over rep"

There is plenty of objective evidence for the over-rep.
You can only have subjective evidence for the explanation, and I have never been subject to any of it.
Sorry.

Using an abbreviation does not constitute racism to rational people.
Using BP saves me 15 key strokes.
At half a second each and given I must have used it over a thousand times, is about two and a half hours of solid unnecessary typing.