New Delhi, Dec. 16 -- In the past year, tens of thousands hostile to immigrants marched through London, chanting "send them home!" A British lawmaker complained of seeing too many non-white faces on TV. And senior politicians advocated the deportation of longtime U.K. residents born abroad.

The overt demonization of immigrants and those with immigrant roots is intensifying in the U.K. - and across Europe - as migration shoots up the political agenda and right-wing parties gain popularity.

In several European countries, political parties that favor mass deportations and depict immigration as a threat to national identity come at or near the top of opinion polls: Reform U.K., the AfD, or Alternative for Germany and France's National Rally...