History, geography and the rapid expansion of extractive industries, especially coal, have combined to produce a unique built environment in Wales, and I'm pleased to introduce this debate this evening. I'm also pleased to allow Hefin David and Suzy Davies to have a minute of my time. 

The terraced housing of the industrial period is present in other parts of the UK, but not in the concentration found in the Glamorgan and Gwent Valleys in particular. It was the product of the rapid urbanisation that accompanied the discovery of the south Wales coalfield. South Wales was the Kuwait of coal, according to one historian, and the coalfield produced just the sort of coal that the nineteenth century required: anthracite for heating; steam coal for locomotion. These were the central parts of the industrial revolution.

In 1851, only 951 people lived in the Rhondda Valleys. By 1881, the figure was 55,000, and, by 1921, 167,000—more than Cardiganshire, Merionethshire and Montgomeryshire combined. Of course, the population growth experienced in the south Wales Valleys drew on rural migration, allowing many Welsh men and women to stay in Wales, if not in their county of birth, instead of, for instance, crossing the Atlantic. And this vast wave of economic migrants had to be housed. There developed, in response to the beautiful, even sublime, geography of the Valleys, something unique. I mean, of course, the ribbon pattern along soaring mountainsides that still today is a powerful and evocative image of Wales, matched only perhaps by the fortress castles of north Wales.