shepherd’s pie a savoury dish of minced meat with a topping of mashed potato (now almost universal) or pastry (in Scotland in former times). In keeping with the name, the meat should be mutton or lamb; and it is usually cooked meat left over from a roast.
The name of the dish conjures up visions of shepherds of long ago eating this simple fare, but the name does not seem to have been used until the 1870s, when mincing machines were developed. The dish itself doubtless dates back much further, and it is generally agreed that it originated in the north of England and Scotland where there are large numbers of sheep. So the common idea that shepherds ate the dish back in, say, the 18th century is probably right.