It's most frustrating when you come across a variety of stamp that you have found, only to find that it is not listed, even after looking in a specialised catalogue for it.
This was the situation I was confronted with some years ago when finding this 4d Guernsey (plain) that has apparently been printed on a cream paper.
This particular stamp was first issued on the 7th of February 1966 and according to the information given in the catalogue with reference to the types of paper used, this cream paper version should not exist and only whiter ones should be found as per SG's introductory notes .........
Here are 2 unmounted marginal pairs as seen in the normal spectrum, the cream paper version being on the left.....
Followed with the same stamps, but as seen under longwave ultraviolet.
According to the figures given there was a combined total sold of 4,415,040, just how many was printed on this cream paper is an unknown factor as in theory it does not exist.
Or does it ?
You decide! WM