They have no idea what to do with them. I saw one group of riot police heading towards rioters and ordering them to "disperse", as though they were a group of nineteenth-century rebels trying to storm Parliament. Of course, the rioters had already done their looting and wanted nothing better than to "disperse" each to his or her council flat, with all the stuff they'd stolen. The police are as clueless as Alicia Silverstone and not nearly as nice.