It was the Bristol-born historian Robert Vaughan, who, in 1843, coined the phrase ‘the age of great cities’, in response to the changes he observed going on around him. Medieval and early modern England had been a land of villages and small towns. Apart from London, which had a population of more than half a million in 1700, English towns were ‘pitifully small’. The second and third largest towns, Norwich and Bristol, with 29,000 and 20,000 people respectively, were both individually larger than Manchester, Liverpool and Birmingham combined. During the eighteenth-century population growth, urbanisation and industrialisation became powerful tides that swept unevenly across the country as technological innovations and inventions stimulated the expansion of manufacturing. One outcome was a reordering of the hierarchy of provincial towns, which had been fairly stable for centuries, and by 1801 Manchester, Liverpool and Birmingham were all significantly larger than Bristol and Norwich. In the new century the growth of towns and cities continued on an unprecedented scale, not only in England but also in the central belt of Scotland and in South Wales, so that by 1851 a majority of people were reckoned to be living in urban areas and Britain was far more urbanised than any other country in Europe.

As people became increasingly aware that profound changes were afoot, they were fascinated and often appalled by what was happening. Vaughan, however, was among those who saw a positive side to it, in terms of greater individual freedom and progress. Debate continued throughout the rest of the century about the nature and implications of urbanisation and what to do about it. In the early Victorian period, in the 1840s, it was the fast-growing northern industrial towns that attracted most attention. Manchester, above all, was the ‘shock city’ of the time, but Glasgow, Liverpool, Birmingham, Leeds and Sheffield were also at the leading edge of the growth in trade and industry that made the United Kingdom the world's dominant economic power. An unintended consequence of the generation of wealth by manufacturing in increasingly industrialised towns was what one twentieth-century observer called the most degraded urban environment the world had yet seen.