When someone (for instance, you) refers to Dean as being "black" it implies that there's some further knowledge of his racial history. Since this isn't detailed in either of the significant biographies, I wondered where your confidence came from. I'm still not sure where it came from, but now I know it wasn't from actual knowledge of the issue, which is what I suspected.
Not to dip too far into semantic theory, but while it holds that Dean's race might have been questioned/taunted circa eighty years ago, it becomes a vacuous truth to classify those opinions as correct today (i.e. Dean was racially abused in the 1920s-1930s = Dean was “blackâ€). It’s a simple logical misstep. The most you can say is that Dean was perceived as being mixed race eighty years ago (to the best of my knowledge, the 'Uncle Tom' remark in the Times obit was in reference to the historical prejudices of the time) and that Everton Football Club did not let that perception influence their decision to employ him. Which, I agree, is a good thing, although it's somewhat deflating to celebrate anyone simply not being racist.
I wasn’t initially attempting to undermine your point. It just read like you knew something concrete and I wondered how.