Britain adopted decimal currency and so replaced pounds, shillings and pence. There were 12 pence to a shllling, and 20 shillings to the pound. During the change-over period, as people gradually became familiar with the new system, people would often have to do a quick conversion in their heads to be sure just how much an item was in the new currency. They might well ask the shopkeeper, how much is that 'in old money'?