As the premier black players of the 'golden generation, I totally understand why Campbell and Cole are held up as the prime examples of the lack of black representation at manager level. Raheem Sterling did so.
The problem I have with that is one comes across as a fundamentally strange guy and the other as thick as pig shit. Now there are countless white managers who fit into either or both camps, we employed one fairly recently so I'm not saying that their skin colour hasn't been a barrier, just that Dwight Yorke, Andy Cole, Les Ferdinand and I'm sure plenty of others would be stronger examples.