Chris , Many thanks for taking the time to reply. Your information was very interesting and answers a question that I should have asked a couple of years ago when I first saw the photo of my Great Grandad. I only realised last night though that I only have a scanned copy of the front of the photo as I returned the original to my aunt who has since passed away - unfortunately the photo has gone awol. At least I have a photo of him which is something which I am chuffed about.
Thanks again for your help !
Cheers
George.
QUOTE (4thGordons @ Nov 11 2009, 10:33 PM)

Hi George yes, very common - it was how photographic paper was supplied to the photographers. They could also have their name stamped, printed or embossed into it.
have a look at page 8 here for some examples.
Chris