having looked back at the sign i'm 99% sure it is the one, the bits which are black on the old photo have a faint black outline and a yellowish tint and are rough to the touch, whereas the areas which are white on both do not. Now i'm wondering if it's the sign on the left or the right!
There were other signs on the alloment years ago, not the sunlight one or the other Blue Cross one though. I seem to remember a massive one which entirely formed a shed roof! and I had a brook bond's tea one as well from there.
Further along on another fence was one which I now recognise as the blue and white Borax one with a picture of a woman on it.
I looked up there recentl and couldn't see any, but it was too overgrown really.