Oh well. Fuck that for a game of tin soldiers then. 
This is only my second post on this thread, which I have been following avidly (huge thanks again to everyone who has posted so eloquently). My first post, pages back, was drawing the comparison between transwomen and Rachel Dolezal - summarise - most people consider RD deluded and wrong, she can't choose her race, and no matter what she does to her external appearance, no matter what she does socially, no matter what she says, she cannot become Black (or African American, or whatever it is she is currently claiming she is).
So to take Sophie Walker's position and apply it to issues of race (and why not?), anyone who identifies as Black should have their rights fought for on the same grounds of race and ethnicity as people who are actually Black? That e.g. the Southall Black Sisters should include White-born people who identify as Black in their remit?
(Sorry, not writing particularly well - tired and about to go to bed, but wanted to get my point down.)