Authored by Connor O'Leary
Following the announcement from the Governor of the Bank of England, Mark Carney, in November 2018 that the new polymer £50 note will celebrate the UK’s achievements in science, there has been much speculation over which British scientist will be the face of the new banknote. Members of the public were then able to nominate candidates to be considered by the Banknote Character Advisory Committee before 14 December 2018. A total of 227,229 nominations were received by the Bank, 991 of which were eligible for consideration by the Committee1. The shortlisted candidates include Stephen Hawking, Alan Turing, Rosalind Franklin, Dorothy Hodgkin and – rather controversially – Margaret Thatcher, amongst others.
Now odds-on with the bookies, Stephen Hawking is the frontrunner to become the face of the new £50 note. Hawking was a prominent theoretical physicist who performed groundbreaking work in physics and cosmology, including the revelation that black holes have a temperature and produce radiation, now known as Hawking radiation. He also became a successful author and science communicator, seeking to make complex scientific ideas such as general relativity and black holes accessible to the general public, most notably writing bestseller, A Brief History of Time, which sold more than ten million copies3.
In 1963, Hawking contracted motor neurone disease at the age of 21 and was given two years to live. Yet he went on to have an illustrious career in academia, becoming the Lucasian Professor of Mathematics at the University of Cambridge in 1979, a prestigious position once held by Isaac Newton in 1663. Hawking was also the recipient of numerous awards and prizes, such as being elected a Fellow of the Royal Society (FRS) in 1974, the CBE in 1982 and the US Presidential Medal of Freedom in 2009. His determination and perseverance in his career despite his decades-long battle with his condition made him a role model and champion for those with disabilities across the world4.
Often labelled as ‘the father of modern computing and artificial intelligence’, Alan Turing is regarded as a pioneer in the development of the modern computer following the publication of his seminal paper, On Computable Numbers with an Application to the Entscheidungsproblem in 1936. During World War II, Turing played a crucial role at the Government Code and Cypher School (GC&CS) at Bletchley Park in breaking German ciphers throughout the war, including his development of the ‘Bombe’ which successfully decoded the messages sent from the German armed forces. It is estimated that Turing’s code-breaking work shortened the war by between two and four years, saving millions of lives. Following the war, Turing was made an OBE by King George VI in 1946 for his wartime services and elected a Fellow of the Royal Society (FRS) in 1951, three years prior to his death5.
Aside from his significant contributions to computer science, mathematics and the Allies’ victory in World War II, Turing is often regarded as a martyr of the LGBT community. In 1952, Alan Turing was convicted of ‘gross indecency’ after having sex with a man and pleading guilty, insisting he had done nothing wrong. As a result, as an alternative to imprisonment, he was forced to undergo chemical castration via injection of stilboestrol (now known as diethylstilbestrol), a synthetic oestrogen (female sex hormone), in an attempt to ‘cure’ him of his sexuality. The conviction forced him to leave his job at the Government Communications Headquarters (GCHQ), whilst the treatment rendered him impotent and caused him to grow breasts. Turing committed suicide shortly after in 1954. It wasn’t until 2013 when Alan Turing received a posthumous royal pardon and in 2017 the “Alan Turing law” came into effect, retrospectively pardoning all men convicted of ‘gross indecency’6.
Rosalind Franklin, who was responsible for much of the research that led to the understanding of DNA, is another prime contender shortlisted by the Committee. In 1952, Franklin and her PhD student Raymond Gosling captured ‘Photograph 51’ which revealed the double helix structure of DNA, perhaps the most famous X-ray diffraction image ever captured. Without her consent, colleague Maurice Wilkins showed this image to Sir Francis Crick and James Watson, two competing scientists working on the elucidation of the structure of DNA. The Photograph confirmed the structure and led to Crick and Watson’s publication in Nature in 1953 as well as their Nobel Prize, without acknowledging Franklin’s contribution. However, after her death, Crick said that her contribution had been critical.
Sadly, Franklin died young at the age of 37 from ovarian cancer. Now, four ovarian cancer charities (Ovacome, Ovarian Cancer Action, Target Ovarian Cancer and The Eve Appeal) have encouraged the public to nominate Franklin as a candidate to the Bank in the nomination period. The charities label Franklin as “one of the unsung science heroes of the twentieth century” and say “since Franklin’s death, there has been a growing recognition for her research into the molecular structure of coal, viruses and, of course, DNA, but lots of people still don’t know who she was”8.
Dorothy Hodgkin was a pioneer of X-ray crystallography, a technique used in the determination of the three-dimensional structures of molecules from diffraction patterns. Significantly, she is the first and only British female scientist to win the Nobel Prize, awarded in chemistry in 1964 “for her determinations by X-ray techniques of the structures of important biochemical substances” such as vitamin B12 and penicillin. Moreover, after 35 years’ work, in 1969 Hodgkin deciphered the structure of insulin after decades of technique refinement, which led to a greater understanding of the molecule and improved treatment for diabetics10.
Hodgkin is widely appreciated as an inspirational role model for female research scientists and as such, the Royal Society celebrates her legacy with its ‘Dorothy Hodgkin fellowships’ for early career stage researchers. Amongst her academic accomplishments, she was elected a Fellow of the Royal Society (FRS) in 1946, awarded the Royal Society Medal in 1956 and became the second woman to receive the Order of Merit in 1965.
Moreover, Hodgkin’s political views, being a socialist and having a strong interest in humanitarian causes, led to her appointment as President of Pugwash, an international organisation dedicated to reducing the dangers raised by scientific research and armed conflict, seeking peaceful solutions to global security threats11.
The new polymer banknote is set to have a range of security features12 and the Bank of England will announce who has been chosen as the face of the new note in summer 2019.
The new polymer banknote
The Bank of England began its roll-out of polymer banknotes in 2016, replacing traditional paper notes. The new notes are made from biaxially oriented polypropylene (BOPP). "Biaxially orientated" refers to the stretching process employed in production, which increases the material's strength13.
The new notes are also more secure, cleaner, waterproof, last on average 2.5 times longer than paper notes and can be recycled after use.
As an anti-counterfeiting measure, luminescent (spontaneously emit light) lanthanide compounds such as those of Europium and terbium are inkjet-printed onto banknotes to create images characteristic of the authentic banknote that are only visible under UV light14. Indeed, the various Euro banknotes use Europium compounds which reveal images of the EU flag, a bridge, a map of Europe and the denomination under UV light (Figure 2).
In the current paper £50 note, such compounds are used such that under ultra-violet (UV) light, the number 50 appears in bright red and green, as well as featuring randomly-spread red and green flecks across the note:
The compounds absorb light in the UV region of the electromagnetic spectrum and emit light in the visible region, so the colour can only be seen when exposed to UV light. The type of luminescence involved in the anti-counterfeiting of banknotes is fluorescence, which arises from singlet-singlet electronic relaxation and is short-lived, so the fluorescent compounds cease to glow immediately after the UV light source is removed.
 Think Science for the £50 note, Bank of England, https://www.bankofengland.co.uk/banknotes/50-pound-note-nominations(accessed December 2018).
 StarChild, NASA, https://starchild.gsfc.nasa.gov/Images/StarChild/scientists/hawking.jpg(accessed February 2019).
 A brief history…, The Bookseller, https://www.thebookseller.com/blogs/brief-history-752141 (accessed December 2018).
 Professor Stephen Hawking, University of Cambridge, https://www.cam.ac.uk/stephenhawking (accessed December 2018).
 Alan Turing (1912-1954), History of Mathematics at Manchester, University of Manchester, http://www.maths.manchester.ac.uk/about-us/history/alan-turing/ (accessed December 2018).
 Alan Turing - visionary, war hero and the only choice for the £50 note, Reaction, https://reaction.life/alan-turing-visionary-war-hero-choice-50-note/(accessed December 2018).
 World History Archive/Ann Ronan Picture Library, https://wha.mediafiler.net/iam/start/wha-archive?fc=browse&queryid=fa7f3996c98d68509806716e2ad772cf&column=7&listview=overview&view=preview&fileid=1&fuid=WHA-060b%2FWHA_060_0996.jpg (accessed February 2019).
 The Nobel Prize in Chemistry 1964, https://www.nobelprize.org/prizes/chemistry/1964/summary/ (accessed February 2019).
 The Campaign to Honour an Unsung Female Scientist on the New £50 Note, Refinery 29, https://www.refinery29.com/en-gb/2018/11/217677/rosalind-franklin-50-pound-note (accessed December 2018).
 Pioneer in X-ray crystallography, Dorothy Hodgkin is the only British woman to have received the Nobel Prize in chemistry, 175 Faces of Chemistry Celebrating diversity on science, Royal Society of Chemistry, http://www.rsc.org/diversity/175-faces/all-faces/dorothy-hodgkin-om-frs/(accessed December 2018).
 Why Britain\'s only female Nobel scientist should appear on the new £50 note, The Independent, https://www.independent.co.uk/news/science/new-50-note-dorothy-hodgkin-female-scientist-nobel-prize-british-penicillin-diabetes-a8630206.html (accessed December 2018).
 £50 Note, Bank of England, https://www.bankofengland.co.uk/banknotes/50-pound-note (accessed February 2019).
 The Chemistry of Paper and Polymer Banknotes, Compound Interest, https://www.compoundchem.com/2016/09/20/banknotes/ (accessed February 2019).
 J. Andres, R.D. Hersch, J. Moser and A. Chauvin, Adv. Funct. Mater., 2014, 24, 5029-5036.
 Invisible fluorescent ink opens new frontier in fight against counterfeiting, http://theconversation.com/invisible-fluorescent-ink-opens-new-frontier-in-fight-against-counterfeiting-40361 (accessed February 2019).