I have told this story before, but it is worth repeating here.
In the 1960's, when I was in high school, my friend had a shoebox full of these notes, exactly the ones pictured. That amounted to several thousand notes.
We decided to sell a few of them at school and threepence each was decided on. A silver thereepence was a bit smaller than a dime. We managed to sell a few hundred of them, with some kids buying a whole bundle, as pictured here.
Eventually, the school authorities got nervous about using the school grounds as a place of commercial business and closed our little activity down, but not before we had made total sales amounting to about 10 pounds. That's about 800 notes, all in crisp flat uncirculated condition.