I haven't personally cooked in the UK so could have the flour thing backwards, but do know I've seen it many times as warnings that one includes leavening and the other doesn't, so it is just one issue when translating recipes across the ocean. I just read (maybe in Shirley Corriher's amazing book :Bakewise: Hows and whys of successful baking?) about Rose Birnbaum translating her American Cake Bible for UK cooks and the flour was just one of the issues she had to adjust. It was enlightening to me because it explained why a few of the fabulous looking UK cookbooks I used never seemed to work right...

See my response on prior thread re: whipping sugar and butter. Also, if you are in UK and the book was written in US (or vice versa) our flours are different and could be causing the problem (basically, in the UK what is called "all purpose flour" is known as "self rising flour in the US), so there could be a recipe adjustment required due to the quantity of leavener that needs to be added.

Old / inactive baking powder? Test by sprinkling a little over some hot water. It should fizz energetically. If not, problem identified.

Hi there, I think you're responding to my request for clarification from this thread : http://www.food52.com/hotline/13104-i-just-made-a-batch-of-cupcakes-they-re-really-heavy-followed-the-recipe-to-a-t-any-suggestions-wh

Well, I don't know the recipe or that book, but there are a lot of possibilities: maybe your leavening agents (baking soda/powder) were very expired? Or perhaps you over-mixed the batter? Or underbaked the cupcakes? Sorry the recipe didn't turn out!