Hats off to tradition. Two of Europe’s major June horse-racing events — Royal Ascot outside London and the Prix de Diane Longines in Chantilly near Paris — drew crowds decked out in fanciful frocks and dapper coattails accessorized by eye-catching millinery. Extravagant hats or fascinators were de rigueur for the ladies while top hats or straw fedoras were favored by the gents. Which country’s race-goers wore it best? You be the judge.