Six years after his posthumous royal pardon for being convicted of homosexual activity in the early 1950s, World War Two code breaker Alan Turing is due to appear on England’s £50 banknote.

The decision by the Bank of England this week is a further move to rehabilitate the image of a man whose pioneering work breaking Germany’s Enigma machine code was overshadowed by his personal life at a time when homosexuality in Britain was illegal.

The banknote concept of a new 50 pond note featuring mathematician Alan Turing is presented at the Science and Industry Museum in Manchester, Britain.
Image: REUTERS/Andrew Yates

During World War Two, the mathematician and computer scientist managed to crack coded German messages, preventing essential supplies bound to Britain from the US from being torpedoed by enemy submarines.

Turing is seen as the father of modern computing and artificial intelligence. However, he took his own life two years after his conviction and undergoing chemical castration.

Bank of England governor Mark Carney presents the image of mathematician Alan Turing who will appear on a new 50 pound note at the Science and Industry Museum in Manchester, Britain, July 15, 2019. REUTERS/Andrew Yates - RC12C30FD230
Caption: Mark Carney announces Alan Turing as the face of England’s new £50 banknote.
Image: REUTERS/Andrew Yates

Turing was pardoned by the Queen in 2013 following a public petition. Bank of England Governor Mark Carney chose him from a list of 989 nominated scientists to become the new face of the £50 note.

His face will appear on the new polymer banknote when it goes into circulation in 2021, along with mathematical formulas, his signature and his quote predicting the future of computing: “This is only a foretaste of what is to come, and only the shadow of what is going to be.”

There are more than 3.6 billion Bank of England notes in circulation - worth about £70 billion - a big platform for a country to make a statement about its values.

So how do countries decide who and what to put on their cash?

1. UK

Image: Bank of England

William Shakespeare was the first historical figure to be featured on an English banknote, back in 1970, but the note ceased to be legal tender in 1993.

It would take until 2017 for a woman (apart from Queen Elizabeth who is on the other side) to appear on a banknote – Jane Austen, on the £10 – and only after a heated public campaign. The woman who led calls for Austen to appear on the note received misogynistic abuse and death threats.

While the choice of Turing will be welcomed by LGBTI advocates, a campaign was launched in December 2018 for the Bank of England to represent the ethnic minorities making up 14% of Britain’s population, using the hashtag #BanknoteOfColour.

Mark Carney said at the unveiling of the new £50 note: “We want to represent as best as possible all aspects of diversity within the country, from race, religion, creed, sexual orientation, disability and beyond. What we have today is a celebration of one of the greatest mathematicians and scientists in the United Kingdom and not just this country’s history but world history.”

2. Euro Zone

The signature of the President of the European Central Bank (ECB), Mario Draghi, is seen on the new 50 euro banknote during a presentation by the German Central Bank (Bundesbank) at its headquarters in Frankfurt, Germany, March 16, 2017.      REUTERS/Kai Pfaffenbach     - LR1ED3G0RJEO7
No national symbols, so what’s on the 50 euro note?
Image: REUTERS/Kai Pfaffenbach

With 19 countries currently in the euro zone, choosing historic figures for banknotes would involve huge reserves of diplomacy.

So instead, the European Central Bank's bills avoid personalities and opt for something less contentious: imaginary buildings. That means no Eiffel Tower or Brandenburg Gate, but generic architectural drawings of windows, doorways and bridges that are meant to symbolize "the European spirit of openness and cooperation" and "communication between the people of Europe and between Europe and the rest of the world".

Each note has a distinct colour and features a map of Europe, the initials of the European Central Bank in nine different linguistic variants, and the signature of an ECB president.

3. United States

United States one dollar bills are seen on a light table at the Bureau of Engraving and Printing in Washington November 14, 2014. REUTERS/Gary Cameron/File Photo                  GLOBAL BUSINESS WEEK AHEAD PACKAGE Ð SEARCH ÒBUSINESS WEEK AHEAD SEPTEMBER 12Ó FOR ALL IMAGES - S1BEUAUFBKAD
Image: REUTERS/Gary Cameron

American $2 bills are nine days older than the country itself. The very first were called Continentals and were authorized on June 25, 1776 by the Continental Congress.

All seven denominations of dollar bills in circulation today feature former presidents - all white men.

The US plans to produce a new $20 bill featuring anti-slavery activist and former slave Harriet Tubman, replacing former president Andrew Jackson, a slave-owner whom historians say was particularly abusive.

4. Japan

If all the 17 billion banknotes in circulation in Japan were stacked up, they would be 450 times the height of Mount Fuji, according to the Bank of Japan.

A Japan Yen note is seen in this illustration photo taken June 1, 2017. REUTERS/Thomas White/Illustration - RC164A33CC50
Image: REUTERS/Thomas White

The 1,000-yen note features the mountain and cherry blossoms on the back, and the bacteriologist Hideyo Noguchi on the front.

While the UK took until 2017 to put a female writer on a banknote, Ichiyō Higuchi - Japan's first prominent woman writer of modern times - has featured on the 5,000-yen note since 2004.

5. South Africa

In 2018, the South African Reserve Bank began circulating banknotes featuring the former president and anti-apartheid revolutionary Nelson Mandela, to commemorate what would have been his 100th birthday on July 18.

New South African bank notes featuring an image of former South African President Nelson Mandela are displayed at an office in Johannesburg January 17, 2013. South Africa's rand was slightly firmer against the dollar on Thursday, a day after miners at Anglo American Platinum called off a strike at the world's top platinum producer.   REUTERS/Siphiwe Sibeko (SOUTH AFRICA  - Tags: BUSINESS POLITICS) - GM1E91H1LMV01
Image: REUTERS/Siphiwe Sibeko

All denominations from R10 to R200 depict his face on one side, and the standard 'big five' animals on the back have been replaced with a younger image of Mandela and scenes related to his life.

6. Canada

In 2018, human rights campaigner Viola Desmond became the first woman (apart from a queen) to appear on a banknote in Canada – on a new, vertical $10 note.

In 1946, Desmond refused to leave a whites-only area of a cinema, and the ensuing court case became an inspiration for the pursuit of racial equality across Canada.

“Banknotes... tell the stories that have shaped our country. Now, each time this new vertical $10 bill changes hands, it will remind us of our continued pursuit of human rights and social justice in Canada,” said Bank of Canada Governor Stephen Poloz.