Henry - Lift up night latch with jointed key Patented
in the specifications as " A loose bit with wards is joined
to to the key, which bit falls when the key is inserted in the
lock is operated from the inside by a finger lift or knob, and
from the outside by a jointed key, which has to be straight in
order to enter the tubular keyhole.
Once the key is inserted into the lock it presses up against a
spring loaded cover and the jointed portion (the key bit) turns
at right angles and can now lift the latch bolt. The key automatically
straightens up when withdrawn.