ComingSoon.net just released some images of the concept art as well as the final renderings of the three Lords and their sons.
A group drawing of The Lords with their first born sons.
Lord MacGuffin and Young MacGuffin
Lord Dingwall and Wee Dingwall
Lord Macintosh and Young Macintosh (whom I believe was named as a nod to Steve Jobs. Lord Macintosh is voiced by Craig Ferguson - a perfect choice).
The Art of Brave book by Jenny Lerew will be released on May 30th - click on the image to purchase from Amazon.