From the looks of the sets shown by Sarah, once you have decoded one lock, the others should be the same, but at a different scale. This will make things easier.
I’d guess (and this is a guess) that you could perhaps look inside the keyhole and learn quite a lot about this system of locks. There are going to be two possible ways it locks:
either the key front presses against something and engages it, or
the key passes completely through a set of wards, and it then turned to engage a single lever arrangement.
As such, you can either impression it with a specially made key blank or try using something long and thin to hit whatever button are there, or you can use some carefully shaped wires to try and access the internals and throw the bolt.
It is a tricky looking thing, though, and you might well need a good non-destructive locksmith. I know a few guys in Spain, but it’s a big country! The advantage of a from-the-UK locksmith is he is far more likely to be able to open a lever lock system like this without damage, since we have lots of lever locks, unlike the rest of the world.
I’d sure like a play with it!
