I've the same problem with blue fish - never seen one I don't like!
I forgot - Brits do it by weight. That sounds about right. My mom still uses a scale to bake many of the things my Grandmother used to make. She figured out the US measurements years ago - but she still pulls that old blue thing out everytime she makes shortbread.
We have alder trees here, too. But, I was thinking you might have them in the LFS around there.