If you have the $:
https://www.abebooks.com/servlet/BookDetailsPL?bi=30107455966&searchurl=tn%3DThe%2BWind%2Bin%2Bthe%2BWillows%26sortby%3D17%26sgnd%3Don%26fe%3Don&cm_sp=snippet-_-srp1-_-title26
Looks about as close as it gets to a true first edition signed by the author.
If there is an edition before it, it would have to be ahead only by months as this is from 1908.
Such a great book!!! Watership Down is my fav, along with Where the wild things are.
velveteen rabbit, lion witch and the wardrobe...
Oh man.. going to have to buy these hardcovers and read with a pipe!
Cap'n, just re-checking: yours is also the unabridged edition with everyone smoking pipes in the illustrations? Same as Odobenus'?
I found a copy with the same cover on amazon, but the publishing date is 2003.
Olkofri, sorry I'm late replying -- be careful of those various editions through Amazon. Many have the wrong cover in the image. You definitely want the 1980.