My thesis is devoted to the investigation of dialect levelling and koinéization in British dialect speech. Historical sound documents from the early 20th century form the basis of my research As an active member of the Königlich Preußische Phonographische Kommission the Berlin Anglicist Alois Brandl (1855-1940) compiled a copious collection of sound recordings of British dialect speakers (all of whom happened to be prisoners of war at the time) between 1915 and 1919. This unique resource was largely forgotten until recently ? in spite of its obvious value as the largest extant database of early-twentieth century British dialect speech. Brandl analysed some of this material in the theoretical framework of classical regional dialectology but did not fail to notice a large number of unpredictable and inconsistent features. The present research will demonstrate that these represent incipient stages of koinéisation and will provide a comparative analysis of early 20th-century and contemporary material to document the extent of dialect levelling and koinéization. As a sociophonetic analysis of ongoing sound change in British dialects, it is unparalleled because of the amount of speech analysed and because of a unique "real-time" depth of almost 100 years. By analyzing the Kommission's recordings, I plan to compile a turn-of-the-century (c. 1900) "Survey of English dialects," which will function as a bridge between the picture painted in Ellis' (1890) classic early work on the dialects of England and the Survey of English Dialects (Orton et al. 1962-1971), which covered the same ground from the 1950s. Ellis' coverage is impressive in that it includes both rural and urban variants, but of course leaves much to be desired if judged by the rigid methodological standards of later dialect-geographical research. By the time the field-work of the Survey of English Dialects got under way, many of the more important recent phonological innovations in British dialects (e.g. glottalization, h-dropping) were already firmly established over wide regions of England. The Kommission recordings, by contrast, represent a crucial state in the development of the dialect landscape in which, using state-of-the-art variationist methods, I can investigate early stages in the emergence and spread of these innovations.