Alan Turing, the pioneering British computer scientist, will feature on the new polymer £50 note design, the Bank of England has announced.
The new £50 note is due to enter circulation by the end of 2021. It will be made of the same plastic material as the latest £5 and £10 notes, as well as the upcoming £20 that will enter circulation next year.
Here, we tell you everything you need to know about the new note, including how to spot a rare one.
Chosen from a list of nearly 1,000 scientists, Turing is being recognised for his role in cracking the Enigma code during WWII at the top-secret Bletchley Park HQ, as well as his pioneering work in computer science and artificial intelligence.
Turing's selection also carries symbolic weight, as the mathematician was persecuted during his lifetime for being gay. His experiences sparked a campaign for the 'Alan Turing law', which came into effect in 2017 and granted a pardon to thousands of men convicted under now-abolished offences.
The note's design contains a hidden message for coders. The numbers 1010111111110010110011000 are written along a ribbon next to Turing's image. This is binary code that can be converted into the decimal numbers 23061912, which alludes to 23/06/1912 - Turing's date of birth.
This is the most recent birth date of anyone featured on an English banknote.
The announcement of a new £50 note may come as a surprise to some.
In 2018, a government consultation found that £50 notes are rarely used in normal transactions, being widely associated with criminals, money laundering and tax evasion.
Despite their reputation, the Bank of England's statistics show there are 344 million £50 notes currently in circulation. That's roughly five per person if they were shared out among the UK population.
As the new £50 notes will be made of the same polymer material as the new £5s and £10s, they should be harder to counterfeit, the Bank of England has said.
Whenever a new note enters circulation, there are new opportunities for collectors.
While coin enthusiasts value rare commemorative designs, those who collect banknotes often seek out unique and significant serial numbers.
Although there's no guarantee that your £50 note will ever be worth anything more than £50, here are the things to look out for if you're interested in starting a collection.
Serial numbers reset when a note's design changes, meaning collectors have another chance to search for those lower numbers.
Any banknote from the AA01 batch could attract interest from collectors.
The earliest notes from this batch are usually presented to dignitaries, so it's rare to find them in circulation. Serial numbers 000001 and 000002 are always presented to the Queen and Prince Philip, respectively. The £5 note that sold for £16,800 was originally presented to 1971 Chancellor Anthony Barber.
While many collectors go for the lower end of the serial number spectrum, some look for the higher numbers.
Since paper £50 notes will no longer be in production, some collectors may go on the hunt for the highest ever serial number - and therefore the last note printed - of this design.
Certain midrange serial numbers can also have collector appeal if they have special significance.
The serial number 888888 has sparked interest in the past as the number 8 is considered lucky in some Chinese communities.
One currency collector who spoke to Which? told us he'd found new £5 notes from the AA01 and AK47 batches.
A scan of sold auction listings on eBay suggests that AK47-batch fivers do in fact sell above face value, but sometimes not by much. In June one sold for £9.50, but another sold for just £5.50.
If you have any paper £50 notes in your possession, you can still use them, as the new plastic notes won't enter circulation until 2021.
The Bank of England will then issue a deadline for the day paper £50s will no longer be accepted in shops.
At this point, you'll have to swap your paper notes at a bank or post office, many of which will do this for you even after the deadline.
If you can't find anywhere that will take your note, you can take your notes directly to the Bank of England in London, as it will honour all withdrawn notes, no matter how old.