Artist Sorting Issue

My question is about the way that Songbird sorts Artists. There are two artists in particular in which I would like to change the way they are sorted but do not know how. The first is "A Perfect Circle", which is sorted with the "P" section. It makes sense to me why it is placed in this section as Songbird is just dropping the leading "A". I would however like to have this band sorted in the "A" section.

The second is a little more confusing to me. The artist "Les Claypool" is sorted with in the "C" section (and all the bands that start with "Les Claypool").



I guess Songbird is dropping "Les" from the artist name but I do not know why. I checked the Metadata and I did not see a "Sorting" tag. Is there one located elsewhere? Is it possible to turn this type of sorting off, or even better toggle it on a per artist basis?