Little bit more done:
Got a rear brake lever in the post the other day. I cut the original mount out from the remnants of the rear frame and mounted it on top of a bit of spare frame tube. This enables me to use the original brake shaft and bracket, so its all very straightforward, only took me an hour or 2.
Next up was a mount for the return spring, this ended up taking me more time than mounting the lever - its just a little triangle shaped bracket which is welded to the frame.
All done now and tacked up - same as the fender mounts - I'll be doing all of the final welding when the frame is stripped down prior to painting, this will make it easier to get into the little nooks and crannys and I can rotate the frame in any direction so I'm always welding on a flat horizontal surface: