You are, literally, saying that everyone is either black or white. It doesn't work like that.
My immediate family and I are all pretty dark. Various dna tests have put me somewhere between 89-99 percent Jewish with bits of Italian, Greek, Persian and Turkish mixed in. My dad, who is really dark, was always stopped and searched when we travelled abroad in the 80s/90s. He was racially abused by people who thought he was Pakistani/South Asian a few times.
It is obvious to me that people don't see me as 'white british'. It's often, though not always, other non-white people who ask me where I'm from. Often Turkish, Iranian, Greek or even Indian people who want to know if I'm 'one of them'.
I became more aware of this when i got together with my husband, who is 100% Welshand looks unmistakably white British. He is treated very differently.
Arabs, Greeks, turks, Iranians, etc. - none of these people are Black. None of them are simplistically White either. Most Jews fall into the same category. We do not get treated the same way as 'white british' people.
Above all, I really fucking hate that we are apparently fair game for any politician who wants to score some points. It was the same way in the 12th c when we were kicked out of Britain, in the 14th c with the Black death, in the Spanish inquisition, the pogroms, the Holocaust. I wish we could be allowed to live in peace