I am of the opinion that the spoon has been adapted rather than specially made (hence the two hallmarks) to compensate for the lack of articulation in the wrist joint.
It was probably made for someone where the hand to arm joint has become rigid or fused or has been fixed in a rigid position by surgery to control arthritic pain.
With a hand and arm in a fixed horizontal position the pivot allows the bowl of the spoon to drop at an angle to make the food ‘pick up’ process easier.
Although the spoon is almost certainly unique, creations and adaptations for a disability are not.
A few years ago a pair of Georgian silver tablespoons (from memory, made by Peter & Ann Bateman) with a blade on one side of the bowl appeared at auction.
Clearly these were made or adapted for someone who had the use of one hand only.
I hope that this helps to solve the mystery.