We’ll start with the proximate:
As mobs attempt to burn down hotels housing asylum seekers, don’t forget Nigel Farage led a campaign to publicise these hotels. He recorded himself turning up at a series of them in 2020 and asked his followers to identify more hotels, saying some residents “might be ISIS”.
Then let’s move backwards:
First there’s been a lot of anti-Muslim propaganda thru the years, including entire TV and movie eras where the most common villains.
Second is a sustained right wing campaign complaining about demographic replacement and stating that immigrants are more likely be criminals than natives.