Commonly referred to as the father of computer science, Alan Turing was a brilliant mind that paved the way for computers as we know them. With a team of code-breakers at Bletchley Park, England, Turing broke the infamous Enigma code used by the Nazis in WWII using an advanced machine akin to a modern computer and invented the idea of a "Universal Machine" that could perform instructions and run programs. His work was integral in founding the field of computer science, alongside being one of the key contributors to Artificial Intelligence with the creation of the Turing Test.  

Despite his incredible feats, Alan Turing was considered guilty of one thing – he was homosexual. 

A crime in 1952, Turing’s homosexuality found him prosecuted for gross indecency and subject to severe punishment. He was unapologetic in who he was and was subsequently forced to take a treatment that would chemically castrate him, all whilst receiving poor treatment from both society and the government. A man whose work saved an estimated 14-28 million lives was ostracized and harassed repeatedly by police and largely confined to his home. 

In 1954, Turing took his own life after eating an apple laced with cyanide. Although he was pardoned in 2013, the loss of Alan Turing is often seen as one of the British Government’s greatest failings. 

Now, the Bank of England has released their latest and last polymer banknote design, featuring Turing as the face on the front. The new note is supposedly the most secure note yet, containing various nods to the mathematician's great work and paying homage to his life. The Bank will also be flying a rainbow flag in his honor above the Threadneedle Street headquarters in London. 

"He was a leading mathematician, developmental biologist, and a pioneer in the field of computer science,” said Andrew Bailey, the governor of the Bank of England, in a statement. 

"He was also gay, and was treated appallingly as a result. By placing him on our new polymer £50 banknote, we are celebrating his achievements, and the values he symbolises." 

In celebration of the release, GCHQ, one of the UK government's main intelligence and security agencies, has announced the Turing Challenge, releasing their hardest set of puzzles yet. Are you smart enough to crack the codes on the £50 note? Find out here.

The English banknote has seen a number of redesigns across the various denominations over the past decade, as the Bank of England switches from traditional paper to plastic currency. New figureheads have made their way onto the notes, including legendary author Jane Austen and ex-Prime Minister Winston Churchill. The £50 redesign is the last to be unveiled, with £50 notes rarely seeing use in day-to-day exchanges. Still, the note remains in circulation as the UK’s highest denomination, and the new note will be issued for the first time on June 23 – Turing's birthday.