17-18th century lock, potentially older, function of v-shape?

[Karel Pelckmans]

Hello all,

I have a question regarding the lock shown in the image.
I found this in a local beguinage. As I do not really know a lot about locks I asked what it was and they told me it is known as a "drunk man's lock" (literal translation from my language). The idea is that the "V-shape" acts as some sort of "guide" so you can find your key even in the dark (the drunk man's lock is a bit wrong, it is a lock made so you can find the keyhole in the dark).
Now this theory makes sense as the lock is from 17-18the century (or even dating back to the 13-14th century is possible, but unlikely in this case as most of the buildings were made in the 17-18th century) and streetlights were not really available.

Now, as I found it an interesting name and liked the theory behind the lock I did some searching, but with not much luck, gained information.

What I did figure out was that this type of locks are very similar (the same?) as gothic locks that often have nice ornaments around the keyhole. These ornaments are purely visual, esthetically and have (as far as I could find) no practical function (as far as I could find out).
So I am wondering whether this "drunk man's lock" theory is something we (further generations) just came up with to give the V-shape a function rather than just being an ornament.

Any ideas on this?

Here is the lock I am refering to and called a drunk man's lock by the local people/tourist-guides.




Two other locks I found at the same beguinage: the blue one, is a more "ornamental" one, more fancy one. That already makes me doubt the "drunk man's" theory.



This lock is an inversion of the "drunk man's" lock, the V-shape is upside down. Now this (and even the blue one) could still serve as a way to guide your key to the keyhole, but to me it makes a stronger case to just assume the shape is an ornament and nothing more.