Sir Isaac Newton 50p (2017)

Aaron West's design turns physics into a neat abstract picture, the Sun at the shared focus of three planetary orbits, and only about 1.8 million were struck for circulation. Outside the Olympic and Beatrix Potter series, no commemorative 50p from 2010 to 2019 had a lower mintage, and it is easy to overlook because there is no character or face to catch the eye. Look for the rings of orbits and the 2017 date. The picture shows a proof strike; the coins in change carry the same design with a plainer finish.