Each year, the slow withdrawal of summer tests a nation's patience and its wardrobe. Across Britain this week, a cold front arriving Tuesday marks not merely a drop in temperature but the quiet, inevitable turning of a season — temperatures falling five degrees, rain sweeping the north and west, and the early commuter reaching once again for a jacket. September, faithful to its reputation for changeability, may yet offer warmer days by the weekend, but the arc is clear: summer loosens its hold, and autumn begins its patient claim.