Thanks. I really must write up a crib sheet.

I find the dating tips useful, but the only way to be reasonably certain is to look at/for features that simply couldn't have been found before a certain date.

In stately homes, of which I look after a few, the locks are often bespoke, & dating is impossible as the locks may have been replaced at any point - many show signs of vandalism, with wards cut away! I opened a C17 lock on a cabinet recently thinking, & telling the staff member, that we were going to be the first people to see inside it for hundreds of years. A fine brass lock, but alas some gibbon had got there before me, & despite a reasonable looking key it had only a trace of a ward remaining, with the other two completely ground away!

I did a restoration on a nice, relatively modern rimlock last week, & again, only the case dimple wards remained. I added new steel pins & made two keys so that it at least would no longer take a blank!

Thanks again for the advice, I *have* used it over the years!