The inclusion of the sonata Z. 807 in 1697 contributes to the overall patchwork character of that publication, since the piece is Purcell's only sonata based on a ground bass and his only sonata à due. In many respects, the work does not belong to the tradition of Italian trio sonata but rather to the tradition of improvised or quasi-improvised divisions upon a ground. Thus, an appropriate title for the piece would be “Two upon a Ground” rather than “Sonata” or “Chaconne” (the latter sometimes being added to recordings of the piece).

The unusual place of Z. 807 within the framework of 1697 and of Purcell's sonatas in general also makes the scholarly discourse around it—analytic and contextual—different from the discourse around the other sonatas. As sometimes happens in musicological research, the odd-one-out receives greater attention than the majority of works, which have a structural affinity among themselves (a similar phenomenon can be observed with relation to Dido and Aeneas, as opposed to The Prophetess, King Arthur, and The Fairy Queen). In Wessely-Kropik's study, Z. 807 is the only work that is analyzed in terms of textural acceleration and deceleration. Studies by Robert Klakowich and, more recently by Andrew Woolley, regarding possible models to and influences on Z. 807, have made it the most studied sonata by Purcell. The purpose of this chapter is to highlight the relevance of some of the techniques discussed in previous chapters to Purcell's ground-bass composition, with an emphasis on plainsong-derived techniques and symmetry, and on their place in the design of Z. 807.

Purcell's ground-bass technique is among the most cross-generic in his arsenal. One may find examples of ground bass works in almost all the media he engaged with—court odes, sonatas, vocal and instrumental numbers in stage works, keyboard music, and songs. However, over the past few decades, with the growing sensitivity to the different functions and patterns of transmission characteristic of each genre, attempts to appreciate Purcell's ground basses across the entire generic palette become rare. It is thus no surprise that articles that dealt with ground technique as a whole were more common in the 1930s and 1940s, whereas in recent years scholars prefer to focus on the way ground technique is implemented in individual works.