The thesis contributes to an established, but largely anecdotal, literature examining the rapid decline of the British car industry's remaining mass producing manufacturer, British Leyland (BL), through the rigourous examination of three key issues raised by historians and contemporaries of the period in relation to the quality of British Leyland's products: (1) 'product-led' decline; (2) losing an advertising war with incumbents, (3) and the imposition of Voluntary Export Restraints (VERs), between the UK and Japan in 1977 aimed at restricting the quantity of imported Japanese cars to Britain in order to protect domestic firms. In order to capture each of these issue, which relate to product quality, the thesis blends primary and secondary sources with the analysis of a substantive data set. The later captures every model-version sold in the UK car market from 1971- 2002 and includes over one hundred and thirty characteristics ranging from the humble cupholder to traffic navigation systems and on-board computers. This is matched to a complete set of firm accounts and model-level advertising expenditures.