“That’s a nice way to start, Jonny,” mutters Thom Yorke, backed by the introductory blast of feedback on “2 + 2 = 5”. It’s a fitting opening for Hail to the Thief, a sixth record that sees Radiohead relinquish some of their trademark fastidiousness for something more rough-hewn, spontaneous, and freeform. It’s an approach that, in keeping with the atmosphere of political turmoil, yields skittering, richly complex songs that perhaps peak with the heady, bitter march of “There, There”.