They do seem to be missing an important point, as my comment there points out:
First generation immigrants aren’t going to rise to the top of the civil service. Their children should obviously have an equal chance to do so.
So, when did the composition of the population reach 7% BME? Or even 11%? And a generation after that takes us to what year?
Would we actually expect the upper levels of the civil service, people in their 50s, to reflect the percentage of BME population yet?
I don’t know the answers to these questions. But they are the first questions I would be asking.
Thinking about this a bit more, we’d need upper level management to track BME portion of the population some 50-60 years ago. Does it?