David Lammy writes about the low number of black students at Oxbridge. I think he underestimates the role of the media in perpetuating stereotypes about black academic performance, for example I remember seeing a comedy sketch featuring a black guy on Mastermind who kept giving comically wrong answers to really easy questions.
Seriously though most of his arguments are demolished in the comments so I won't go over every wrong fact and unsafe assumption- although the fact he uses different definitions of "black" for the number of people who apply and the number accepted is telling. The fact that other minority groups are statistically over represented is also interesting.
However one thing that is always worth remembering is that the differences in academic performance are evident from before children even start school, so it isn't obvious how higher education institutions can have proportional numbers of different groups.
3 hours ago