William Herschel, telescope-builder, observer, and pioneer of deep-sky astronomy, was a professional musician for the first half of his life. He served as a boy bandsman in the Hanoverian Guards, and then fled to England in 1757 to escape the French. We are well informed about his time as a musician in Bath (1766-1782), which culminated in his discovery of Uranus, as his sister Caroline, chronicler of the family, was with him for most of these years. But little has been known of his previous time in the north of England (1760-1766), or of why an obscure jobbing musician should have been offered a prestigious post in Bath. This article is devoted to this episode in his career. (1738-1822; referred to in what follows as "William") was the preeminent constructor of large reflecting telescopes at the end of the eighteenth century, and he himself used his various instruments to discover some 700 double stars and 2500 nebulae and clusters. As a theoretician, he saw gravity as the prime agent of change in deep space, and he described the life cycles of nebulae, stars, and star systems. But, amazingly, he was a musician for the first half of his life. His closing years in music, during which he became a dedicated amateur astronomer, are well documented, partly because he shared his home in Bath with his sister Caroline, the chronicler of the family. But the pre-Bath years he spent as a jobbing musician in the north of England have been shrouded in mystery. In what follows, we explore this episode in William's life, and suggest how it was that a novice organist was offered the prestigious post that took him to Bath.