When selecting node edit mode, I can see the current ‘green square’ cut start points.
If I set shape start point/s to a different node which is indicated by the blue arrow, when I check in the preview the start point/s are correct but I would have thought/liked the new start point position would have been reflected in the node edit mode which it is not?
Perhaps I’m just going mad…comment’s welcome thanks 
The start point (blue arrow) and shape start point (gren box) are not the same thing. The green box is determined by how the shape was made. The blue arrow does go to this location by default, but it can be changed to any other point as you found out. If you want / need the green box to align with the start point, using the node editor select the point you wantthe green box, break apart at that point then rejoin the shape and that point will be the new location of the green box. That will also move the blue start arrow to that location. But like I said they are independant of each other.
Thank you for taking the time to give a comprehensive reply 