Leek and Cheddar Sausage Rolls

My father, Prue’s younger brother, makes the best Glamorgan sausages, and he used to do so in industrial quantities when I was a child, so he could pull them out of the freezer at a moment’s notice to feed his vegetarian brood. He made them by eye, measuring everything in handfuls, so this is not an exact replica of his recipe, but it’s a good approximation. Wrapped in flaky, buttery puff pastry, they’re absolute