Unfortunately firms, especially top firms, don’t care about diversity except for ethnic diversity. This means you can be a middle class black man and get onto black only schemes regardless of your background.
For this reason I would have only diversity for social mobility and disability only imo. Non-RG would come under social mobility.
It seems as though you want to retract from the lack of ethnic diversity in the legal profession with this comment.
Ethnic diversity is to increase the number of Black, Asian and Minority Ethnic students, as social mobility is to increase the number of students from working class backgrounds.
I think what you mean is that, law firms perhaps pick persons who still fall within the 'elite' category, so a private school educated black candidate is picked over one that grew up on a housing estate. Similarly, a white candidate whose parents did not go to university, can still be very wealthy (e.g. Richard Branson's children and Sir Alan Sugars children), and so does not truly represent what this category was set up to reflect.
I agree there is gaming by law firms, but that does not take away from the fact that there is a lack of black men in the legal profession. If they don't start with the private, grammar, RG and Oxbridge black male candidates, then there really isn't any hope for the rest. Though, I do agree that they are gaming and this should be called out.