Can't see how they are not legal tender even in Scotland when that is what the cash dispensers ... errrrm ... dispense!!
Royal Bank of Scotland, Bank of Scotland and Clydesdale Banks all produce their own notes.
I have been able to use them without any problem in all the High Street Stores all over England and Wales, however it is at the discretion of the Manager of a business as to whether they will accept the Scottish notes. This is purely because of the high number of counterfeit notes that have been around the past few years.