Individual Scottish banks.
Scottish banknotes are currently issued by three separate banks; Bank of Scotland Clydesdale Bank Royal Bank of Scotland
No, Scottish banknotes never were legal tender, and Scotland is the only place where they will be accepted. The currency of Scotland is the Pound Sterling (GBP). All Scottish banks have the right to produce their own banknotes, but only three do. Strangely, all Scottish banknotes are not legal tender anywhere including Scotland. They have more of the standing of a promissory note (in Scotland) and there is a strange legal loop hole in Scottish law that allows this to occur, fortunately. This is simply wrong. Scottish and Northern Ireland banknotes should be accepted within the UK but if accepted outside Scotland, they are returned by UK banks to Scotland. The fact that many have the word "sterling" on them is the biggest clue here. I have frequently spent Scottish currency in England.
The UK consists of England, Northern Ireland, Scotland and Wales. The Bank of England is the sole issuing authority for banknotes in England and Wales. Scottish banknotes may be issued by the Bank of Scotland, the Royal Bank of Scotland and the Clydesdale Bank. Four Northern Ireland banks practice their right to issue banknotes, being the Bank of Ireland, the First Trust Bank, the Northern Bank and the Ulster Bank. The banknotes of all Northern Ireland and Scottish banks are backed by the Bank of England.
De La Rue PLC print all English banknotes under licence from the Bank of England.
The Bank of England has the sole responsibility for issuing English banknotes.
Northern Ireland and Scottish banknotes are issued by commercial banks rather than a central banking authority and therefore have the status of a promissory note rather than legal tender. By agreement between the banks of the United Kingdom, all banknotes are treated as legal tender. However, shopkeepers and other business people are not obliged to accept Northern Ireland and Scottish banknotes.
Irish banknotes are not legal tender in Great Britain. Northern Irish banknotes are not legal tender in England and Wales, but by mutual agreement between the banks, are considered as "acceptable tender".
This will depend on which bank issues the notes. The Royal Bank of Scotland and the Bank of Scotland have both had notes printed by De La Rue based in Basingstoke, Hampshire. De La Rue are a printing company which specialises in printing currency. They claim to offer banknote technology for over 150 world currencies and have even printed Euro banknotes for several Eurozone countries.
No, the Bank of England issues banknotes. The Royal Mint produces coins.
The currency of Scotland is the Pound Sterling (GBP) and Scotland uses British coins as produced by the Royal Mint. All Scottish banks have the right to produce their own banknotes, but only three do. Strangely, all Scottish banknotes are not legal tender anywhere including Scotland. They have more of the standing of a promissory note (in Scotland) and there is a strange legal loop hole in Scottish law that allows this to occur.
Yes, you can use American money in Scotland, but it may not be accepted by all businesses. It's recommended to exchange your American dollars for British pounds in order to easily make purchases and transactions while in Scotland. Many places in Scotland also accept credit and debit cards for payments.
See the link to the Bank of England.