Following up to Jen

>while ago someone was talking about shepherds pie and cottage pie.

You don't need anything but potato and butter for SP/CP topping
IMHO. No reason you cant add milk if the particular potatoes come
up very stiff. The top browns very well in the oven without egg.
Add cheese if you fancy it.
Theres only one hard and fast rule, if its lamb its shepherds, if
it aint its cottage. (BTW, in UK creamed corn as an ingredient
would be seen as very odd).

Citations:-
BS45823 Naming conventions, potato covered caseroles and related
matters HMSO 264963 7/6d.
--
Mike Reid
Name that pie, recipe and field guide:-
"http://www.fellwalk.co.uk/londonfood3.htm"