Paper is only good as the government or the bank behind it. I also find your comment regarding the default on payment of specie for paper interesting, because yes the government pulled a fast one and nobody complained, they just obediently followed along and took paper as money.
I would rather imagine if for instance you took an RBS £1 in to their or another bank there in Scotland and asked for a £, you are going to be handed a pound coin, or a pile of them. Sure are not going to get a sovereign, though one could wish for one.















