... was not withdrawn from circulation until 11 March 1988.
The pound coin was introduced in 1983, and this may be where the confusion arose. The Bank of England stopped issuing pound notes in 1984.
The pound note is still in circulation in Scotland, although rarely seen nowadays. Interestingly, banknotes have never been legal tender in Scotland.
('Legal tender' actually has a very narrow meaning: a debtor cannot successfully be sued for non–payment of a debt if he pays into court in legal tender. Anything can legally be used to settle any transaction – you can use buttons if you want to, as long as both parties agree. In theory, you might even get a court to accept something that isn't legal tender; but this would leave you open to the possibility of being sued for non–payment.)
© Macclesfield Quiz League 2019