Similar Richard. Mine is parallel to the hoop however. I tried turning the threaded part, but that just started to wind the cable up. Am interested in how yours is set as mine is on max loose extension with no thread showing within the rectangular piece. I thought it was a bolt initially.
That looks pretty standard, but surprised yours appears to have maximum slack. When you apply the handbrake, is there still some extra clearance in the handbrake lever slot? I like to be able to insert a couple of fingers into the spare space.
As far as adjusting is concerned, you don't wind the threaded bit up that is attached to the cable. First undo and back off the locknut that is outside of the rectangle, hold the hexagon part immediately adjacent to the cable with a spanner to stop the cable winding up, then with a box spanner (or long nose pliers if you are lucky) screw up the nut inside the rectangular bit along the threaded shaft. This is where you may have to flex the rectangular bit to get the box spanner in. Finally, screw up the locknut.