This thesis is a practice-based study of organ improvisation in the Anglican cathedral tradition in the UK. I combine exercises in the practice of improvisation in a number of musical styles associated with Anglican Church music, with documentary and sonic evidence of improvisation in this tradition, and interviews with some key practising improvisers. Context for this study is further provided by a comparative study of the very different improvisation practices prevalent in Germany and France. In Part 1, Chapter 1, I first identify the French and German traditions of liturgical organ improvisation, from the perspectives of stylistic development, liturgical and pragmatic demands on organists and characteristic types of organ. Chapter 2 outlines the stylistic development of Anglican voluntary improvisations, whilst considering improvisatory aspects in Anglican hymn playing and psalm accompaniment. These comparisons enable me to define certain characteristic features of Anglican liturgical improvisation. Chapter 3 consults sonic evidence of Anglican organ improvisation and elucidates important influences on the development of Anglican liturgical organ improvisation from the later nineteenth century to the present. The conclusions to Part 1 suggest that a distinct Anglican tradition of liturgical organ improvisation does indeed exist. Whilst there are significant differences in the expectation and demands of the organists between Anglican and continental traditions, there are nonetheless many opportunities in Anglican worship where the discipline of stylistic improvisation could beneficially be applied. I conclude that organists in the Anglican tradition could benefit a great deal from the practice of stylistic improvisation. Part 2 introduces and explains my methods in developing and realising stylistic improvisation using models from the historical traditions of Anglican church music (from Tallis to Mathias). The attached DVD is a means of recording, assessing and disseminating this new-found knowledge. Chapter 4 discusses my own processes in developing and executing historical stylistic improvisation. Chapter 5 presents a portfolio of my own professional practice, which includes the DVD project, in which I apply the continental approach of stylistic improvisation to the Anglican tradition by identifying key formulae and performing improvisations in the style of English organ composers. Whilst some Anglican organists in the UK have been influenced by continental traditions, the lack of extensive formal training in stylistic improvisation in the UK can be compensated by systematic study of composers' styles and the regular practice of improvisation in these styles within Anglican worship. This is not primarily a historical study of improvisation, but a critical and contextualised examination of improvisation practices in the Anglican tradition since the late nineteenth century, and a practice-based testing of the potential of applying continental methods of preparing and executing stylistic improvisation to the Anglican context as a means of strengthening and enlivening its efficacy. I thus debate questions of value and functionality, finding much of value both in the Anglican tradition of free, modal improvisation, and in the disciplined approaches of French and particularly German improvisers. I note the pedagogical implications of my research, arguing that organ improvisers should develop a consummate musicianship which combines musical disciplines (such as analysis, harmony, counterpoint and aural training) in the act of improvising as opposed to the compartmentalised approach of teaching these disciplines presently the norm in UK colleges and conservatoires. In a series of appendices, I show the responses of fifteen British organists in a survey on 'Organ Improvisation in the UK'. Furthermore, I present a list of commercially published organ improvisation CDs by British organists, an outline of English tutor books on organ improvisation, a transcription of my improvised Ceremonial March from CD 3, track 1, a list of all the reviews of my DVD/CD Ex Tempore, as well as handwritten notes on Anglican improvisation by Martin How, together with other miscellaneous documents.