UglyUncle, I don't really accept your justification for the absence of a Scottish indicator. The relevant word in the clue is not specifically Scottish; all Chambers has to say is '...in Scotland especially'.
In the past there was no rule about this and it was left to the setter's discretion, which I thought was fine. Then the rules changed (not only in the Listener). The problem with rules is that they need to be consistently applied, and that is not always the case. I would much prefer these things to be left to the setter's discretion. It's not as if the rule makes clues easier to solve - in fact I can recall some examples where it made things harder.
On the "train tracks" puzzle, I have traced a path that conforms to the numerical and other constraints, and I have traced another, slightly different path that conforms to those same constraints. Oh dear!