Aiming to complement and complete the repertory of early secular polyphony edited by John Stevens in Musica Britannica volumes IV, XVIII and XXXVI, Secular Polyphony 1380–1480 includes music from MSS copied in England as well as music by apparently English composers in MSS from the continental mainland. It also includes a large number of pieces for whose origin there is no clear proof, but which are presented here in an appropriate musical context on account of their sources, form and style suggesting an English origin. The contents are presented in groups of material comprising MS collections from Cambridge University Library and the Bodleian Library, music by composers including Bedyngham, Dunstaple, Frye, Galfridus de Anglia, Hothby, Morton and Robertus de Anglia, works ascribed to Alanus, music from John Baldwin's Commonplace Book, English fragments, longer works before 1440, works related to the English repertory 1450–1480, and early arrangements of O Rosa Bella.