Just a minor technical query; out of curiosity only, as it doesn't cause me any problem; [and in fact I only discovered it comparatively recently].
From the forums' full Index page, I normally go straight to a desired individual forum (' - historical', ' - current', etc.) : No problem.
But I notice that if I try going (from the main index) to what looks like next-level-down by clicking on a section main heading, e.g. "Signalling discussion" [ as displayed as the central item in the chain "Board index » Signalling discussion » Signalling - historical" seen above that forum ] : - ("Other discussion" or "Who is online" act the same way); ... it results in the topics of that section being listed quite normally, but with the same main heading below them, followed by "You do not have the required permissions to read topics within this forum".
As I say, it causes no actual topic access problems (that I am aware of), as all topics seem freely accessible direct from the full index : Just thought it worth raising out of interest.