'I received the Queen's command to appear at Windsor that very day.' John Thomas (1826-1913) rose from a modest tailor's family in South Wales to the post of harpist to Queen Victoria. His influence as a musician and composer is little known today, but he was admired by Berlioz, befriended by Byron's daughter, brought Mozart's Flute and Harp Concerto to this country, pioneered the artistic tour and encouraged Welsh music, not missing a major Eisteddfod for 40 years. The harpist, Sioned Williams, talks to Paul Vaughan about her quest to track down the man and his compositions for solo harp which were the drawing room hits of the day.