Interesting article, and it's right that most of the resentment and criticism comes from people looking for a way to express their discomfort with an uppity black woman at the heart of the establishment.
Look at the criticism she received when made patron of the national theatre. A former actress, with a double degree in theatre studies and international relations was deemed less able to do the task of hob nobbing with actors and donors than a woman who's never done a proper job or worried about paying the rent.
Let's not even go to all the comments about how annoying it apparently is that her hair doesn't act like a white person's.
Britain has a problem with black people not knowing their place or appearing sufficiently grateful.