Most people think, with very good reason, that Frank Sinatra was the best popular singer, as well as the best interpreter of the Great American Songbook, who ever lived. Save for a few voice lessons, he was also self-taught and had no musical training of any kind, which makes it all the more remarkable that when not singing, he dabbled in conducting — and was singularly good at it, too. “I’m really a frustrated conductor,” he once went so far as to confess to Nelson Riddle, the legendary pop-music arranger who was one of his closest musical partners and was himself on the podium for several of Sinatra’s greatest albums. Comparatively few of Sinatra’s latter-day fans, however, know about this side of his musical personality, for he was too modest about his conducting to regularly feature himself in that capacity. Fortunately, he did record seven albums as a conductor, one of which, Peggy Lee’s The Man I Love, is widely regarded as the finest record she ever made.