I'll note I'm white, but not native British, and none of the people in question tend to object to me being here. Often they make that explicit, by e.g. telling me that I'm "one of the good ones" or similar.

What instead often happen when they hear I'm Norwegian is a complete mask-off moment where they start explaining their favorite racist thinking to me, assuming that since I'm from a group they like, apparently I'm expected to agree with them (I do not).

My main exposure to anti-immigrant thinking face to face in London over the last 25 years have been repeated incidences of people who "just have concerns about immigration" revealing their racist motivations to me without me even asking them.

In other words: I don't buy it for a second when people try to insist it's immigration they care about, rather than seeing non-white faces.