Thanks for that link. I'll have a browse.
There isn't any particular tools I have in mind although I have a mark on an old auger bit shaft that I would like to identify.
My thinking is that if it has a mark on it is should be of reasonable quality, compared to a lot of the rubbish monkey metal that is around now. Although I know that old makers did have second and third quality goods, I think that even they are going to be better than the stuff you find in the local hardware store ( if you still have one ) or the diy sheds. It's also part of the interest I suppose, to get a bit of the tools history/story. And I don't collect, I buy to use. So there still has to be some life left in the tools to warrant me purchasing and restoring them to useful condition.