After historic Tory loss due to loss of faith on immigration issue, Tories elect a black woman to set their party right

Pretty much. The hope is that this unbiases the racial bias of minorities and shaves a non-trivial part of the left's voter base away.

Of course, even ignoring the history of these groups, such ignores that the bias for these parties in those groups is often reinforced less by skin colour or the like and more by social pressure and media domination.

In an American context for example, black people vote for the Dems because they're the (current) bonafide black party as imparted by community leaders and the media at large. If a black person runs for the Republicans that's nice and all but it's a black person running for the non-black person, whatever at best, Uncle Tom at worst. A cracka running for the Dems on the other hand? That's just a huwite man in THE black party.