King Charles III was officially proclaimed Britain’s monarch Saturday in a pomp-filled ceremony steeped in ancient tradition and political symbolism — and, for the first time, broadcast live online and on air. Scores of senior British politicians past and present, including new Prime Minister Liz Truss and five of her predecessors, gathered in the ornate state apartments at St. James’s Palace for the meeting of the Accession Council. They met without Charles, officially confirming his title, King Charles III. The king then joined them, vowing to follow his mother’s “inspiring example” as he took on the duties of monarch. The...