Many years ago when I was a clerk I clerked for a parish council consisting of two very different wards; one very rural and one semi urban. They were one parish council but two distinct areas with separate ward members. One precept was requested and for some costs it was pretty difficult to split where the expenditure actually arose (office costs for example). I did, however, attempt to separate out costs in my accounts for some years in an attempt at separate budgeting and it turned out to be a good move as ultimately, following a boundary review, two separate parish councils were created and an agreement made to divide the reserves of the original council so that the new one had some reserves to start off with. My separate accounts helped inform that decision.