Recipes are an area that is quite hard to shift to metric because often recipes are handed down from previous generations. Simplistic conversions are easy, but will often create slight problems in the recipe - eggs, 'spoon based measures, etc., break the rounding that goes on in moving between measure systems.

Cookware passed down too could help to promulgate Imperial measures, we have a heap of tins that are inch-based measures. They're small effects but they add up.