When I was a lad I had a friend, Robert, whose dad was the paraffin man. The paraffin man drove his lorry from street to street and customers would take out their paraffin cans for a refill.
On the back of the lorry were two taps. The regular paraffin was one and three a gallon. The premium paraffin was one and six a gallon. According to one of our snooty neighbours, you got better heat from the one and six paraffin and it smelt better.
When asked what was the difference, the paraffin man would say, “that one is one and three and that one is one and six.”
One day I went to to the depot on the lorry with Robert and his dad. I was impressed that they were able to get both types of paraffin into the lorry through the same valve and from the same storage tank.
Time moves on and today they sell electricity in the same way.