Thanks for that Jeff. I ended up printing the photos and then scanning them back on to the computer again. I'd say that's why the hallmark isn't as clear here.
I'll check for the year on the hallmark and that will give me an idea of who could have had it. But as I mentioned, my great grandfather was in Scotland during WW1, so he could have got it to remind him of his time there.
Thanks for all your help Jeff. One more mystery solved :).