Hello, everyone! Just came across this May 12, 2011, article from The Guardian UK. Ran a quick search of the TwainWeb archives, in case I missed seeing this, and did not happen to find a previous mention. Apologies if this has already been discussed. Here is a link: 
“Rare Edward Ardizzone illustrations of Huckleberry Finn rediscovered - Pen and ink drawings for 1961 edition surface in publisher's study” 

M. L. Christmas