I serviced a 1927 bungalow last night with a working rim night latch and a bit-key interior, and it got me wondering: what’s the oldest mechanism you’ve run into in a lived-in house? I like to retrofit these with discreet smart cylinders so the owner keeps the charm, gains bump resistance and auto-lock, and walks away happy.
Ran into a true warded rim lock with a skeleton key in a lived‑in 1910 foursquare — older than your 1927 rim night latch. I’ll leave the warded set as “show” and add a hidden smart deadbolt (Level Bolt) plus a London bar on the strike to stiffen the frame; if they insist on the rim, swap to an anti-bump rim cylinder and drive it with a Nuki inside; see Warded lock - Wikipedia. @OP you ever try that mix, or do you stick to discreet cylinders on the existing latch and leave the bit‑key alone?
I still see 1890s mortise sets; for your “rim night latch”, shim the case and mind backset with smart cores.
Spotted an 1880s lever box lock still used — for the “bit-key interior”, fit a clutch smart cylinder; test return spring…