A common interpretation of "National" to mean "English" Mcem.
Even AgeUk is really Age-everywhere-in-Uk-except-Scotland-we-should-have-called-it-Age-England-and-Wales. Their scope and boundaries stop at the border. They were unaware of the error in their title until Age Scotland pointed it out to them, too late to change it, of course.
Until and unless legislation changes things, Scotland is a part of national UK I am not pro-independence, but I can see how assumptions like these do make some people think that if they are invisible to "National" organisations, they might as well be completely separate.