Is it not more a case of settlement not mattering so much because lime
mortar was all they had?

Well, whichever way. The effect is the same.

Our Victorian semi seems to have settled quite a lot before the final
fit had even been done, judging by one upstairs doorway that is a good
inch lower on one side. The original architrave has just been cut to
fit a less than 90 degree corner on one side and the door is trimmed to
fit..

My Edwardian terrace has a doorway or two like that, on the rear "extension"
bit. The BCO didn't mind us building a loft conversion on top without so
much as investigating the footings. Half the houses in our street have been
converted without problem, so they have our street down as not requiring
foundation investigation.

Christian.