CEOP withheld an area breakdown.
I think we know the over-rep is an issue of the Midlands and North.
I think we know why ethnicity was probably not recorded in so many cases.

CEOP found a large over-rep NATIONWIDE in cases where ethnicity was recorded.
The numbers were so great that even if every unrecorded ethnicity were a different demographic, there would STILL be an over-rep.

And then there is all the other evidence.