Inspired by lines from Byron's Childe Harolde, John Thomas's Premier Impromptu, Le Soir is dedicated to the poet's daughter, Augusta Ada, Countess of Lovelace (1815-1852). Best known as a brilliant mathematician, she was also a gifted harpist, and after hearing the twelve-year-old John Thomas play, she became his patron, subsidising his studies at the Royal Academy of Music (1840-1846). As a token of his esteem and his gratitude, John Thomas dedicated many of his published harp solo compositions to her, Le Soir being one of the earliest of these.