Outnumbered

Summer has come early to London this year. The city's parks are parched, its riverside pubs and cafés packed. Londoners are enjoying the weather, but some detect in its unusual generosity the hidden curse of global warming. A similar pessimism greeted the life sentences handed out on the last day of April in a sticky courtroom to five British-raised terrorists for their involvement in a conspiracy to commit mass murder. The branch of the U.K.'s security service known as MI5 foiled the plot before any blood was spilled, but its success cloaks a tragic failure. That, at least, is the judgment...