Browning had apparently somewhere come across the word twat—which meant precisely the same then as it does now—but pronounced it with a flat a and somehow took it to mean a piece of headgear for nuns. The verse became a source of twittering amusement for generations of schoolboys and a perennial embarrassment to their elders, but the word was never altered and Browning was allowed to live out his life in wholesome ignorance because no one could think of a suitably delicate way of explaining his mistake to him.
