 BBC commissions included the orchestral works "Mutations I" (1969), "Aurora" (1973), "Scenario" (1975), "Praeludium" (1975), "Memoria" (1978) and "Limina Lucis" (1982).Other works include a "Piano Concerto" (1989), "Duologue" for violin and piano (1971), "Scena" for violin and piano (1988), "Teneritas" for flute and piano (1997), "Sonante" for clarinet and piano (1986 - for Thea King), "Cantus" for clarinet and piano (1996), a "Piano Trio" (1983), a "Wind Quintet" (1986), several mixed ensemble pieces including "Time-Passage" (1977), "Stratos" (1979), "Epitaph for Abelard and Heloise" (1979) and "Litania" (1993), piano works including "Tableau" (1980), "Fantasy" (1983), "Threnody" (1990 - all for Jana Frenklova), "Trilogy" (1992), "Musica Aeterna" (1997) and "Sereno" (2004), organ works including "Mutations II" (1971), "Momentum" (1977) and "Esultante" (1977 - these last two for Gillian Weir), "Dreams, Dances and Lullabies" for harp (1990), "Silentia Noctis" for high voice and piano (1989), and many choral works, notably "Carmen Paschale" (1981), "Hymnus Ante Somnum" (1985), "Sequentia ad Sancte Michaele" (1985), "Westminster Mass" (1990 - for Martin Neary), "Recordatio" (1999) and a sequence of eleven "Sacred Chants" (2005).Lewis's music is characterised by rhythmic energy and harmonic complexity alternating with extreme stillness; latterly his music has tended towards greater simplicity and tranquility and it often appears to inhabit a twilight world of dreams.