Whether Scottish notes are legal tender or not does not change alter their inherent value but it dictates their legal function. Credit cards, cheques and debit cards are not legal tender either but it doesn't stop them being used as payment. Only a minuscule percentage of Scottish and British trading is carried out using legal tender. Just because something is not legal tender certainly doesn't imply it's illegal to use. So... to answer answerbok's question, No the �50 is not the UK's highest banknote, �100 is... however �50 is the highest "Legal Tender" note...