I saw "The Battle of Britain" in a cinema at a NAAFI in Germany as a boy. (Over 40 years ago). This was about the time, or just before, the change from the pence and shillings to the decimal sub division of the coins that add up to a pound.
Here's an idea: the Battle of Britain coin ought to be issued as a five shilling coin (sixty old pence), once called a crown. It's not as though anyone would be spending this coin, so why not issue it in a currency contemporary to the time of the event?
Well, they didn't ask me, and I'm on the other side of the pond, butt it seems the better idea.