This thesis outlines and explains the historical background of West Gallery church music. This is a style of music sung in British town and country churches during the period c1700-1850, and which differs in style and function from that sung in cathedrals and similar places of worship. Volume 1 studies in detail the contents of a set of sixteen part books penned mainly by William Shepherd, a singing-master active in the Isle of Man in the early decades of the 19th century. These are referred to as the Colby collection, after the village in the south of the island where they were discovered. They contain 91 metrical psalm settings, fourteen hymns, eight anthems, four canticles, three Anglican psalm chants, and other miscellaneous material. Most of the settings date from c1720-1820.

A Critical Edition of the music occupies Volume 2, which aims to reproduce as closely as possible the scores from which Shepherd copied the parts. It is intended to enable performance in the manner of Shepherd's musicians, but notes differences from the composers' likely intentions. A printed or manuscript comparator is provided for all settings which have been found in another source, which is the closest in detail that can be found. Missing parts have been completed with reference to the comparator, and all differences from the comparator have been noted. There are commentaries on each setting, and on the style and technique of West Gallery music both in general and as manifested in the Colby collection. All musical and non-musical material in the books is indexed and cross-referenced, to show where any setting or other material may be found, as well as Shepherd's likely order of copying the settings into the books. Conclusions are drawn about Shepherd's general manner of working, and the reasons for the differences between Shepherd's versions and their likely origins.