On April 6, 1974, millions of people from Dublin to Helsinki and Palermo gathered around radios and televisions to root for their countries, but this wasn’t the Olympics. A British woman clad in pink introduced the contest in English, then French. One by one, acts from 17 countries took the stage, decorated in high ’70s style. Olivia Newton-John, draped in a long blue gown, crooned for the United Kingdom. Peret strummed a Spanish guitar, rumba-style, and wiggled in black velvet bell-bottoms. Six men wearing sweater vests sang hopefully in Hebrew: “there’s enough air for one country or two.”The music was…