The sense of occasion around flamenco guitarist Paco de Lucía’s return to London was palpable. The Royal Festival Hall was heaving. Queues at the bars before the show and during the interval were three or four deep. Spanish was everywhere. And that was good to hear. Paco de Lucía is a hero in his country as much for interesting political reasons as he is for purely musical ones. London-based compatriot fans were not going to miss this.