"When animator Hardie Gramatky left the Studio and moved to New York his apartment window looked out on the tuboats on the East River. Almost immediately he found a character like those he had animated. He called it Little Toot, sold the story to Walt, then went on to write book after popular book about the adventures of the youthful tugboat." - Illusion of Life, pg. 503
So that explains the amazing color and personality in these paintings. Looking for more 1950's-era illustration? Check out the Flickr group The Retro Kid, started by Ward Jenkins. Retro Kid features illustration from all sorts of thigns from the mid 20th century - album covers, toy packaging, food labels, etc. Also check out Vintage Children's Books, another Flickr group with hundreds of awesome pictures focused solely on books.
Now for the illys!
P.S. Has anyone figured out an easy way to download lots of pictures at once from Flickr? It's such a pain to click on each thumbnail for the larger version, right click, save, etc...Let me know if you have!