One thing that really annoys me, is going into an English branch of my Scottish bank, with Scottish notes and having the teller examine the notes like it was foreign currency or look slightly suspicious! On one occasion  I  had the manager tell me that they couldn't accept them because they hadn't received notification of the issue of new notes?! Of course this is all less hassle than actually trying to spend the Scottish money in a shop!
*NB This Billy Connoly £1000 note is for illustrative purposes only, and that he only appears on the Scottish £12.50 note.