London was the largest of the great cities of the European ancien régime. Historians of the period invariably mention it, frequently describe it, and occasionally analyse it. But, despite their efforts, very little is known about London during the eighteenth and early nineteenth centuries. We have some knowledge of how the national economy adapted to the growth of London, of how the growth of London affected the specialisation of agriculture, industry and mining far beyond London, of London's role in banking and international trade, of the patterns of migration caused by the size and attractions of the capital. But we know much less of the reverse situation – how the national and international economy affected London, how developments in banking and trade, in law and government affected the developing economy and society of the capital. ‘The capital cities’, wrote Braudel when describing the eighteenth century, ‘would be present at the forthcoming industrial revolution, but in the role of spectators. Not London but Manchester, Birmingham, Leeds, Glasgow and innumerable small proletarian towns launched the new era.’ But the nation's capital could hardly be irrelevant to the new industrial era – it was far too large and important to be ‘isolated’ – and much of this book will be seeking to analyse the connections. Industrial revolution or not, late eighteenth–century London had more steam engines with more horse power than Lancashire; mid nineteenth-century London remained by far the largest manufacturing city in the country.