When the news first spread on Friday that Rishi Sunak was planning a speech outside 10 Downing Street, the Westminster rumour mill went into overdrive: could this be the moment Sunak cut his losses and called an election, hoping that George Galloway’s victory in Rochdale pointed to a Labour vulnerability? No 10 aides were quick to kill such chatter, making clear that the speech was about recent events. But Sunak’s warning about the “poison” of extremism could still set the tone for the Conservative election campaign to come. The prime minister used the 10-minute address to warn of a growing...