British names and addresses were written on the reverse, as happened with some English notes, and numbers were written on the front – duplicating how a bank teller would mark the value of a bundle.[54][55] Four grades of note quality were introduced: grade 1 was the highest quality, to be used in neutral countries and by Nazi spies; grade 2 was to be used to pay collaborators; grade 3 was for notes that were to be possibly dropped over Britain; grade 4 were too flawed to be of use and were destroyed.[56]