"Sachs, mein Freund!" Bryn Terfel has sung extracts from Hans Sachs's music for years, and the character always seemed well suited to his warm voice and air of easy humanity. But he didn't unveil the complete role until this season, in the very production of Die Meistersinger that visited the Proms last night. Terfel proudly puts Welshman after his name, and he promised the country's National Opera that they would get his first Sachs. Six thousand listeners in Albert Hall spent most of the afternoon and evening for the privilege, just over six hours (imagine the ones in the arena who had to stand), with scarcely a handful leaving early. Terfel raises sheep at home, and it takes a golden fleece to hear him in Covent Garden, the Met, or Salzburg. Here he was cheap as chips but musically priceless.