when buying bank notes you need to make sure that the grade is what they say it is, so if a note is ef then need to make sure that it is ef as the value of a lower grade is a lot is the high end notes.
B277 Helmeted £5 note A01 Unc
cat value Unc £430 Ef £200
so if you paid ef money the note need s to be ef as a lower grade when you come to sell is woth a lot less
for grading please check are shop for grading