The radical American anti-racist campaigner Tim Wise has an interesting designation for what he does and what other white anti-racists do. He calls himself a 'white ally'. Wise argues not for white anti-racists to speak for people of colour, but to develop a critique of white privilege from within. The point should be to strengthen the position of racially-conscious Black Americans by providing a critique of the same white male power-structure from a white perspective. I agree with this priority: to undermine white racial consciousness in its manifestations. The other aims that we have to consider were summed up well by Theodore W Allen. As part of the conclusion to his review of David Roediger's book Wages of Whiteness (1991) the Marxist historian and economist Ted Allen listed the four basic challenges that the anti-racist has to meet:
First, to show that white supremacism is not an inherited attribute of the European-American personality. Secondly, to demonstrate that white supremacism has not served the interests of the laboring-class European-Americans. Third: to account for the prevalence of white supremacism within the ranks of laboring-class European-Americans. Fourth, by light of history, to consider ways whereby European-American laboring people may cast off the stifling incubus of 'white' identity.
This is from the starting-point that the historical relativist critique of race as a social construct does not go far enough in unsettling the roots of race as a formation of social control. Likewise, Allen rejects racism as a natural occurrence among white people towards the Other. Actually the point of his work is to provide a historical account for race in specific historical conditions: namely, slavery. As a Marxist historian Allen is concerned with the degree to which white working-class people have undermined their own interests by pursuing racial interests over class interests. The first victims of racial oppression are those immediately subject to it, the second victims are those who blindly align themselves with the oppressors. For example, trade unions in the US were incredibly weaker because they had, for a long time, a white-only membership policy. White privilege (a concept Allen coined) is not to be understood as the literal privileges of white people, but the relative advantages gained through divide and conquer.
The colonial and racial oppression of the Irish provided the impetus to presuppose a 'common interest' among English people which may circumvent the class antagonism and even render it harmonious. This is why Karl Marx was right to situate the struggle for Irish national liberation was, effectively, the struggle against the English ruling-class which could open up the space for the English working-class to shake off the chains of class oppression. Ultimately, the British ruling-class managed the crises of its colonial outpost through various methods, eventually leading to a partitioned compromise, and to this day leading to a peace process. The reunification of Ireland has been postponed and by now the thrust of British capitalism lacks the need for racial oppression in Ireland. We can say that the material circumstances have changed, but that doesn't legitimate the cause of a united Ireland as that was always a just cause. It's just no longer linked to working-class emancipation in the same way.