Hello,  Thought I'd challenge a topic tonight. I was looking at GB EDVII today and while many years ago I studied these and catalogued these I am still questioning if I got the stamps catalogued correctly. Anyone any tips or helpful ideas.???    The above is SG 230 and SG 284.. ( maybe not best reproduced in scans but there is a real colour difference)

Sometime it is easy if there is a clear date on the post franking. Yet more often than not it is difficult, in my view, to determine a De La Rue printing from a Harrison or even Somerset House printing. Yes perforations can help. But that is about it, or is it?  Anyone with more experience than me who can offer a comment on these. Sometime the catalogue value can be significantly different.
I catalogued hundreds many years ago, and by shade and am now questioning how accurate was I

hope to hear from you if you know about these issues. And if you are collecting them just give some thought to those stamps where there is an significant price difference between issues.

Michael