There seems to be several observations of this kind. I myself am on an expedition to find out about the Wilkinson old blade.How interesting. I'm old enough to remember the Stainless Revolution (1965?) Maybe I had been duped by Gillette into tossing my blades after one shave, but I do know that the Wilkinson Stainless gave better shaves for a longer time. I do this from memory.
I do have some inside information as to why this would be the case, but that will have to wait until I find out if the blade I'm using will deliver. There seems to have been around at least a few varieties of these, including the repacked US version. This was, according to my source, largely an effort to avoid customs fees.
Of course all of this is theoretical in the sense that these blades are no longer available in greater numbers.