In July 1998, when I was working on a large piece called Havoc for the 1999 Proms, I decided to use a theorbo (or chitarrone) in the score. Since my technical knowledge of the instrument was non-existent, I contacted the theorbo-player David Miller, who was booked to play in the Proms performance. He kindly showed me how the instrument worked, and I began writing Groundwork as a technical exercise for myself. Hence one meaning of the title; the other being that the piece is a set of variations over a ground bass.

Since the theorbo has eight diapason bass strings – which are plucked like those of a harp, not stopped with the left hand – it seemed sensible to use these for the ground bass, which consists simply of a rising eight-note scale using all diapason strings in turn. This ground is stated at the beginning, and developed through sixteen variations. The first seven are straightforward, except that some of them compress the ground into itself. The remaining variations are in stretto – gradually overlapping each other, with the ground beginning one note earlier on each reappearance. The climax of the piece comes at variations ten and eleven; variations twelve to fourteen bring things gradually down to earth; variation fifteen is quiet, putting the decorated ground in canon with itself (in octaves, using the top and bottom strings of the instrument). The last variation strips the ground of all decoration, putting tight scrunchy chords above it. The piece ends with the lowest diapason string (G), a quiet ripple on the other seven diapason strings, and a final high harmonic (G again) to tell us that our journey is over. The piece lasts about six minutes.

2008 Giles Swayne