Not everyone will know the answer to this one. The ingenuous ones will guess at a colour.
The £5 note is green, and has Elizabeth Fry at the back.
The £10 is orange, and depicts Charles Darwin and a bird.
There is no £15 note.
The £20 is purple, and shows a bust of Adam Smith the Economist, and the observation
"The division of labour in pin manufacturing : (and the great increase in the quantity of
work that results)"
Adam Smith (1723-1790) has contributed greatly to economic thought, and I wonder whether the above bears a clue, either to reverting to things such as pin manufacturing and the division of labour (specialisation) or whether it is a precursor to evolution in this Digital Age, when information can be disseminated instantaneously and en masse.
But the observations of Adam Smith shall continue to inspire progress in many economies, especially in Africa and Asia, where bookshops are still busy, poetry is enjoyed by more and more, and people do use pins and paper clips. Gilt paper clips.