Not much is available in terms of biography for McKinstry. Apparently she was quite the violinist when young and she later studied art with Rodin. Yet, she suffered with tuberculosis of the spine, and eventually turned to illustration as her occupation.
MacKinstry had many productive years as an illustrator, and her style, which, to my eye, was influenced by William Blake, has a charming simplicity. Art Deco styling seems to be prevelant in her work, but I'll let you decide.
I'm not sure about which tales the images below are from, so just enjoy!