The meaning of this word is often mis-understood in the British Isles. Instead of meaning an attractive woman, it in fact means the polar opposite.
A Crumpet is in fact a horrifically ugly mess of a woman, who bares some similarities to a Crumpet. E.G: A cratered face, A greasy face, A short rounded physique. A Crumpet is in fact a woman, who a man should never touch with a bargepole. If a man does 'Eat a Crumpet,' he should lose all respect and all social status.
Male #1: *Wretches* Look at that mess on the other side of the road!
Male #2: What a crumpet. I'd never spread my butter on that.
Male #1: *Wakes up in unfamiliar bedroom. Looks at the woman lay in bed next to him. Instantly thinks 'What a filthy crumpet!' He then legs it to the nearest exit.*