Caerphilly a pale, almost white cheese called after the Welsh town of that name, otherwise famous for its ruined castle. The Welsh justly claim the cheese by origin, for Caerphilly became a cheese-making centre in the first half of the 19th century; but most Caerphilly cheese is now made in the English counties of Somerset and Wiltshire.

There were two reasons for this move. Welsh population growth around the start of the 20th century increased the demand for milk in Wales, so less was available for cheese-making; but the demand for cheese had also risen. Across the border the makers of cheddar, who had ample supplies of milk, saw a chance to expand their activities and speed up their financial return by starting to make Caerphilly too. Cheddar takes a long time to mature, whereas Caerphilly ripens in 10 days. Nonetheless, a revival of the Welsh farmhouse version of this cheese in the 1980s has ensured that its Welshness (as caws Caerffili, caws meaning cheese) continues to be recognized.