The String Quartet No. 15 by Robert Simpson was composed quickly in the summer of 1991 and dedicated to the Vanbrugh Quartet who had developed growing association with Simpson's later chamber music. This work is cast in one continuous movement and is relatively short. The overall mood is tough and turbulent and, as with much of Simpson's later work, the chief roots are a collection of intervals - a minor seventh (both ascending and descending) and a sequence of falling minor seconds dominating. Another feature of this work is that most of the phrases proceed in contrary motion to another instrument (one voice moving up whilst the other moves down).