Rim lock from the 1830s. The logo isn't clear on this lock.
This is from a similar lock (or mabye a bit older, because the top lock has "Patent Expired" where this one hasn't.) shows the arms of William IV pf the United Kingdow (reigned 1830-1836). Made in the UK, these locks were exported to Australia (where this one is) and the USA.
This particular lock is on one of the doors of the service wing at the National Trust's Clarendon.
The lock has two parts. The handle move the latch at the top, which lets the door swing open. The key turns the bolt at the bottom, which stops the door opening . The handle will still move the latch if the bolt is in place, but the door can't open.
In this lock, the turning the handle moves the latch up, so it will fit into the slot in the strike and open. Here the bolt is across and so the door is locked.
From the outside" handle and key hole. The bolt is drawn back.
Now the bolt is out.
This door also has a latch.