I've got no idea Goosey.
We've got plenty of these lovely looking 'orange' flowers growing in parts of our allotment. I've always wondered what they were called but would never have thought it would be scarlet pimpernel.
And even odder, whilst looking on the internet to see if I could find any reasons for the choice of name, (I only had a quick look so could easily have missed the vital info) I came across a blue
version....... which is also called a 'scarlet pimpernel' .
Most odd and unimaginative.