Ironically, the Brexit affects mainly immigration from Europe, which is nearly all white. Immigration from the British Commonwealth, which is mostly non-white is not directly affected at all. So to the extent that Commonwealth immigration replaces EU immigration, Britain will be less white because of the Brexit.
It’s simply that self-determination is called “white identity” when white people practice it, even if the effect is to make policies less based on race.
The dark people gathering in Calais to get into Britain aren’t from the Commonwealth; they have no need to take that approach. They are from other Third World toilets, having crossed into southern Europe and made their way to Anglo-land...