Actually, I think that ,technically, Scottish notes aren't even legal tender in Scotland (!) but it is true that they are being accepted in shops more in England (my wife has to go to Edinburgh on business frequently and has no trouble using Scottish notes up when she's back here). I the "old days" you could only change them at banks. In Anglesey, because of the Ireland to Holyhead ferry, Irish coinage always used to be acceptable where it was the same design as UK BUT since the value of the punt to pound has fluctuated I think that is less true nowadays.
RtS