An excellent question. I did some poking around. Take a look at this link:
http://www.conlanpress.com/html/art_graphics.html
According to this, the chief animator was one Hidemi Kubo. If you scroll down to the bottom you can see some examples of the concept artwork that he did. some of it is even still up for sale from Conlan Press!
Anime News Network's Enclycopedia also credits him as an animator for The Hobbit and the Return of the King. His most significant work for a Japanese project seems to be his role as the animation director for Mazinger Z.
