This thesis consists of a portfolio of five score-based compositions and a commentary associated with each work. There are two instrumental works and three vocal works. The two instrumental works are String Quartet No. 2 and Three Winter Landscapes: Triptych for Orchestra. The three vocal works are Winter Pass (for high voice and piano), In Memoriam (for soprano, flute, clarinet in A, violin and cello), and Marvellous Sweet Music (for two sopranos, two clarinets in B flat and two cellos). Winter Pass is a song cycle on texts by Edward Thomas, while In Memoriam comprises five settings of different war poets, namely, A. E. Housman, Edward Thomas, Leslie Coulson, Richard Aldington, and Willoughby Weaving. Marvellous Sweet Music sets texts from The Tempest, by William Shakespeare. There were two primary considerations in the composition of these works. The first (poetic) element is concerned with how musical sound is made to become a representation of a real or imagined landscape. While in the two instrumental works the landscape is entirely imagined, the landscape in the three vocal works is very much suggested by the texts. Particularly in the two song cycles of war poetry, the texts are very expressionistic, and I attempt to re-create something of the vividness of the poets’ writing. The Shakespeare settings, by contrast, perhaps represent a blend of real and imagined: to the characters within the play, their world is very real, but it is a world imagined by Shakespeare. The second (technical) element is concerned with how the music is actually constructed. My primary consideration here was to blend and juxtapose a variety of different compositional techniques: a hybrid tonality. These techniques include (but are not limited to): traditional tonal harmony (e.g. major, minor, and extended triads), non-functional harmony, controlling levels of perceived consonance and dissonance, multi-tonality, and free atonality. The appendix to the thesis contains my Harmonic Method on Scales of Increasing Intervals, a set of synthetic scales that can be used to create a set of thirteen four-note chords, as well as several earlier works which give context to the present ones.