Hi Ian,
I think that this actually is a "crooked knife" functionally as it clearly fits in the hand to be used as a single-handed draw knife. It has some age to it, but I would hesitate to put this particular example of the tool before the first half of the 20th century and I would similarly hestitate to identify this particular example's cultural origin.
A couple of good links I found to "crooked knives":
Mo-co-ta-gan: Crooked Knives
Mocotaugan: The Story and Art of the Crooked Knife