There were pre-drilled holes in the top of the DeDion tube indicating the riveting points for the brake line. However, these holes were not the correct diameter to accept a 3mm rivet and needed enlarging.
After the holes were drilled out, it was a a simple matter to rivet the brake lines into position, paying attention to the different directions of the P-Clips on the left and right hand side. At this point the flexible brake line was attached to the T-Piece and covered in rubber hose for the necessary protection.
Fitting the brake lines to the DeDion
The chassis and the end of the DeDion was protected with pipe lagging and towels respectively - additionally cardboard was attached to the back of the fuel tank. (With the benefit of hindsight, some protection on the back of the Differential would also have been useful).
The manual indicates that the DeDion should then be put into position in the chassis by sliding it in from the left hand (near) side. Doing so creates the need to get the brake line T-Piece past the Differential and the extent of the threaded stud makes that very difficult if not impossible. It then became obvious that a better approach is to slide the DeDion into the chassis from the right hand (off) side. When that was attempted, installation was easy.
Fitting DeDion from right hand side / offside of the chassis
After the DeDion was in position, the flexible brake hose was attached to the main brake line in the chassis. The fixed brake line uses a connector to pass through the chassis cross-rail - once the fixed line was bent to a suitable position (to deliver the copper line into the connector along the connector axis) the flexible line was attached.
Flexible brake line attachment