He has made several collaborations with poets, providing instrumental music to complement spoken words, including "Lares" (1972) with Michael Longley and "The Sound of Time" (1984) with Charles Tomlinson. The first of these was with his contemporary Seamus Heaney, "A Lough Neagh Sequence" (1970). Warren wrote: " I knew Seamus Heaney quite well – we were both young lecturers at the Queen’s University of Belfast – and I thought of him then, before his coming to international fame, as essentially a deep-rooted Irish country poet. He didn’t want his poetry to lose its own “music” by being sung, and I was happy with this because, as an outsider to his tradition I felt I could not readily penetrate it with my music so closely. Hence the decision not to set his sequence as song but instead to have the poems read and to bring out their almost ritualistic long term structures with the use of overlaid piano interludes." Heaney made a recording of this version of his poetry with Warren's music in 2011.