The hunt to find the rioters and the people who incited them began the moment the first brick was thrown. But the efforts to catch them will last weeks or months, and involve super-recognisers, specialist software, video doorbells and, in a few cases, criminal stupidity. A dizzying number of newly convicted rioters and online agitators were this weekend waking up in a prison cell on the first day of their sentence. Of the more than 700 arrests made so far, about 300 people had been charged by Friday night, with more arrests and court appearances on Saturday. Still hidden, for...