There are at least 90 Facebook accounts using the name of Enoch Powell, the late Conservative MP who warned in the 1960s that migration to Britain would produce rivers of blood. Many of the accounts appear defunct, their pages filled with old links to videos that have since been removed from YouTube for “violating [the site’s] policy on hate speech”. The videos have titles such as Fire Up the Ovens and White Man Marches On. Other accounts continue to post racist bile.

A few clicks on Google produce even more sinister results. Last September anti-fascist activists discovered a new extreme right-wing website that invited newcomers to take a 25-question “membership exam” in order to be admitted to the group’s private material, which included guides