The rear rim brake is on after some great work by my LBS (as usual!) -
It works really well and today it passed the big test of riding down hill from school fully loaded with the two boys and the school bags on board! It has no where near the stopping power of the front disc brakes of course but on the descents it slows me down quite smoothly. When heading into corners it also works well at smoothly reducing speed where as the front discs tend to 'swerve' a bit when trying to brake in turns. So just a matter of getting used to them and being careful not to overuse them on long descents and risk heating up the rims to much.
I also now have another parking brake thanks to utilising the old brake handle that used to control the front disc brakes. Here it is on and then off-
The brake mount is very secure with just the two hose clamps in place so I have decided to not worry about the bolt meant to go through the top as this would greatly interfere with the wheel lock on the reverse side of the frame. For added strength though I will put two more hose clamps on the upper parts of the brake mount in such a way that they don't interfere with the wheel lock.
The wheel lock went on with a bit of encouragement - I had to mount it on a slight angle to allow clearance for the hose clamps. Because of this angle I had to place a few washers behind it to bring it out from the frame slightly to allow free movement of the locking mechanism -