At the turn of the nineteenth century only 600 000 people lived in Wales, but by 1901 this figure had almost quadrupled to over two million. This population boom is impressive enough, but it was far from uniform across Wales. Most rural counties saw a moderate increase but the South Wales valleys saw massive leaps in population, with Glamorgan witnessing a ten-fold increase from 71 000 to 860 000 a century later.

Welsh heavy industry was in its heyday. It was Welsh slate that roofed houses the world over, Welsh coal that fired the industrial revolution, and Welsh products in iron, steel, copper and tin that helped build modern Britain. All these industrial workers needed housing, and it no surprise therefore that there was a lot of building going on in nineteenth century Wales.

The result, of course, was distinctive rows of terraced homes in the areas where industry was booming – which meant in particular the South Wales valleys. When many outsiders think of Wales they picture first the industrial valleys of Glamorgan and Gwent, as romantically depicted in 'How Green was My Valley'?. Athough there are rows upon rows of Victorian terraced workers’ homes, it’s a tough job to find a house that’s in anything like its original condition – but Y Ty Cymreig found an excellent example in Llwynypia in the Rhondda.