Thanks Nick
Yes I agree that it might have been better posted in an open discussion, however, the picture is just a 60 year old snapshot of my parents. It is a fascinating picture as it's a colour print taken in 1950 at a time when rationing was going on in Britain. My parents were abroad then. It is regrettable that I couldn't post it on the forum, but there is no railway content.
As for longevity, I've seen Victorian prints that were as clear as originally printed. Probably more luck than anything.