For clarity for the people who don't want to read, this is actually multiple related scandals.

First is the fact that "coloured" people were specifically banned from any role apart from domestic servants.

Then we have the fact the royal family will not acknowledge that ban properly, and refuses to say when it ended.

Then there is the lack of evidence of ethnic minority employees before the 90s.

And then that ethnic minority employees are still entirely absent from senior roles.

And finally that the Queen lobbied (sucessfully) until at least 2010 to be allowed to discriminate against ethnic minorities without legal repercussions.

(Bonus that she also went to great lengths to keep the lobbying and its result secret)