Some time back I bought another one of these from an English dealer and had a problem with an attribution to the Cocos (Keeling) Islands. We discussed them on the old forum and nobody was quite sure where they came from.
Well, I guess they do come from the Keeling Cocos Islands after all. The seller notes that there was an air strip in operation on the Cocos Keelings during WWII, which is probably the source of these knives. Can't be too many of them around.