The British viola player James Boyd, versatile in all repertoire, founded the London Haydn Quartet in 2001 out of a passion for Haydn’s quartet masterpieces and a desire to play them in historically informed style. The freshness of sound, achieved using gut strings and classical bows, is evident from the outset. The result is light-footed, witty and intelligent. Now progressing through the canon for Hyperion, this volume contains the six works of Op 50, the “Prussian”. The variety is formidable, from the economy of No 1 to the zany invention of No 5 to the restless exuberance of the well-known “Frog” (No 6). Pure joy.