This is getting fun now.
This picture shows 16395 (Barneys) and 16392, both new to the same owner!.
Note the brake is on different sides. It looks however that the water lifter is on the nearside on both?
This is mine (15489). Brake on offside. As is the water lifter.
This is 21629. Brake on nearside, water lifter on offside
As Barney noted in messages last night. The area is very congested.
I actually now think that the as built method of fitting the lid is a small strip that fits on the top of the pocket towards the back, with two bolts down into the two drilled holes that you can see in my picture. The lid then hinges off that.
The downside of that, due to the small size is you get a hinge right under your boot when steering.