Thanks Ron. Your scan certainly shows the same colours. I checked Gibbons and there is no mention of any colour variations for this issue. So now we know that there are at least 2 out there. lol
Well, we can just wait for comments, as the collective (pun intended) knowledge on these boards is extraordinary. And if there is no good explanation, there will assuredly be some carefully crafted yarn forthcoming (we are even more impressive at that)
alas what has happened is that the middle was printed in a fugitive ink (to prevent cancel removal/ fraudulent reuse) and the colour has been washed out. This is a problem on many stamps printed in green by the printer (Thos. De La Rue & Co) who printed these.
Interesting comment. Were all stamps printed with the fugitive ink or only a select number? Ron's scan shows 4 stamps that were presumably treated in a similar manner yet only 1 is washed out.
Comments
Well, I see the same thing on the right stamp of this group so the changeling idea is less likely