I would leave him out as well.
To me, I think the main source of the problem is that "Artist" is ambiguous. Composers, performers, painters, graphic designers, photographers, mixers, et. al. are all artists, but they are responsible for different parts of a release.
We already see that problem with classical music and the CSG where we emphasize the composer more.
This discussion is really about that same issue
and this is also related to that ambiguity:
To me, the album artist(s) would be the ones most responsible for the music (or sounds) produced.
For this album, I think the Prince of Wales is the primary artist responsible for the sales of the release.