Update (23 March 2014): John Garth has kindly notified me that Westin's biography was published in English (Tove Jansson: Life, Art, Words — The Authorised Biography) early in 2014.
In 2007, Boel Westin (Professor of Literature at Stockholm University) published the Swedish-language biography Tove Jansson: Ord, bild, liv (‘Tove Jansson: Word, Image, Life’). Swedish-speaking Finnish author Tove Jansson is best known for her books about Moomin. Among Tolkien enthusiasts , she is (in)famous for her illustrations to the second Swedish translation of J.R.R. Tolkien's The Hobbit (Bilbo - en hobbits äventyr, 1962; cf. Anderson, p. 395).
Westin is the first researcher having been given access to the entire archive of Tove Jansson, and included in the book is the publication for the first time of the correspondence between Astrid Lindgren (Swedish children's book author, renowned for the Pippi Longstocking series) and Jansson about the preparation of the illustrations for The Hobbit.
When the publishing house Rabén & Sjögren was planning for a new translation of The Hobbit, Lindgren (who was working as editor for the children's book department at Rabén & Sjögren) wrote to Jansson in November 1960:
“When reading the book, one can clearly see the illustrations, made by Tove Jansson; it is evident that this will be the children's book of the century, which will continue to live a long time after we are dead and buried.” (Westin 356)
Lindgren perceptively understood the importance of Tolkien's book. And Jansson, who had illustrated a translation of Lewis Carroll's The Hunting of the Snark (Snarkjakten, 1959; she was also to illustrate Alice's Adventures in Wonderland in 1966), saw in Tolkien an equally large challenge: she accepted the commission already within a week.
The illustrations were sent during the summer 1961 to Lindgren, who replied in July 1961:
“I'm so glad for your wonderful, little Hobbit, it's impossible to describe in words. Tiny, ingenious, and sweet – exactly how he should be, and he hasn't been portrayed like this in any edition.” (Westin 360)
Jansson had invented a new method for drawing the illustrations for The Hobbit. She tried to get away from the Moomin-style by using “accurate strokes with the pen and carefully filled spaces” (Westin p. 359). She wrote to Lindgren:
“The possibility to escape from my own technique was to draw on paper of bad quality (for which I didn't have any respect) and to freely draw many copies of every figure – 20, 40, or 60 times, until it looked somewhat free. You will understand. Then I glued together the results. Hence a lot of the vignettes look like patchwork, bit it cannot be seen in print.” (Westin 359-60)
Concerning the approach of illustrating The Hobbit, Jansson wrote to her life partner, Tuulikki Pietilä, just after accepting the commission:
“The figures are banal: dwarves, gnomes, fairies, dark-elves. But the scenery is luring in its macabre cruelty ... Haunted woods, pitch-dark rivers, a moon-lit moor with burning wolves.”(Westin 359)
Rather than focusing on the details of the characters (she thinks of making them “rather tiny” and perhaps inventing other kinds of “gnomes and fairies”), Jansson is caught by Tolkien's description of the landscapes, which she tried to portray in her illustrations.
According to Westin, the edition illustrated by Jansson did not become the success the publishers had hoped for. The illustrations received a lot of negative critique: “one saw Jansson where one wanted to see Tolkien” (Westin 361). In the opinion of many reviewers, Jansson had apparently not managed to distance herself enough from the world of Moomin and had neglected to strictly render the characters as described in The Hobbit, .
As far as I know, no comments by Tolkien on Tove Jansson's illustrations have been published. Since Tolkien in several letters offered his opinion about illustrations for various editions of his books, it wouldn't surprise me if we'll one day see something dug up from the archives.
Anderson, Douglas A. (ed). The Annotated Hobbit. Houghton Mifflin: 2002.
Westin, Boel. Tove Jansson: Ord, bild, liv. Schildts: 2007. [Quotes from the book freely translated by M.T.]