Paper money as we know it first appeared in 7th century China - hundreds of years before anywhere else - but it was in Europe that this type of currency really started to move forward.
The precursor of paper money in the UK was the running cash note, which gained popularity in the 17th century. You took your gold coins to a local goldsmith for storage and got a receipt that could be redeemed for your money. Gradually, rather than a promise to pay you the amount stated, running cash notes began to state "or bearer", making it possible for you to exchange your cash note for goods, with the bearer confident that a bank would swap it for real money.
The big change came in 1694, when King William III passed the Bank of England Act, which established the Bank of England as the world's first national bank. This was a way for the King to get a cash advance so war against France could continue.
Pre-printed notes appeared in 1855 and carried the line: "I promise to pay the bearer the sum of...", which did away with the need for the chief cashier to sign them all by hand.
Early banknotes were one-sided and black and white, bearing little more than a denomination and a promise to pay. But WWI brought the look and feel of today's money closer.
The need to preserve gold bullion meant the Government was willing to issue very small denomination notes, so the Currency and Bank Notes Act passed on 5 August 1914 introduced ten shilling and £1 notes.
Apparently, the first notes were something of a design dog's dinner and they were redesigned shortly thereafter. David Lloyd George, Chancellor of the Exchequer at the time, was happy with the results, which he said made it easier for the public to spot forgeries.
Throughout the course of WWI, the design of the new notes gradually became more aesthetically pleasing. Colour was used, with the Houses of Parliament pictured on the back of the £1. Impressed, The Times declared: "In design it is an entire departure from the old, which as an artistic production it leaves far behind."
The second great leap in modern banknote design was the appearance of Queen Elizabeth II on the £1 note in 1960, designed by Robert Austin, professor of engraving at the Royal College of Art. Britannia, who had previously fronted banknotes, was consigned to the reverse and replaced in 1970 by a different historical figure on each denomination of banknote.
Artist Harry Eccleston designed the somewhat contentious Series D notes in 1990. Gone was the young, radiant Elizabeth, to be replaced by the Queen as she was then: in her 60s, staid and, said some, looking a touch frumpy.
In 1993, the series underwent a minor redesign after it was decided that some of the notes were not distinctive enough. Today's notes, designed by Roger Withington and featuring a slight modification of the Queen's portrait by Andrew Ward, are known as Series E.
The design process
Banknotes are designed through an iterative process using bespoke CAD software. The Queen's portrait, however, comes from hand-engraved plates, and is printed onto the money by a process named Intaglio. This technique, which is also used to add the lettering to the front of the notes, involves pressing ink into the paper at incredibly high pressure, making the design appear embossed. Offset litho and letterpress are also used.
Today, the threat of counterfeiting informs almost every aspect of the notes' designs, from the barely visible watermark, incorporated into English paper money since 1697, to the specialist paper - made of a special cotton-linen blend - first created by Henry Portal in 1724.
The famous faces make notes familiar, but they are a security feature in themselves - it's apparently easier to detect inaccuracies in portraits than in the geometric designs used in days gone by. Similarly, fine line work is employed to make the notes more difficult to copy. The metal strip made its first appearance in 1943, when the Germans attempted to destabilise the currency with forgeries during WWII.
Other features present today include foil holograms, fluorescent colouring and microlettering. The Bank of England also consulted with the Royal National Institute for the Blind to ensure notes were easily recognisable by the visually impaired. As a result, the numeral size was increased on all notes and different geometric symbols introduced for each denomination.
"Finding the right banknote in your wallet is easy due to two very simple factors - colour differentiation and clear, bold typography," says HeathWallace creative director Simon Webb. "How many people realise it or appreciate it is not important, but you can guarantee that if these features weren't present then finding a fiver as quickly as you can today would simply not be possible."
He also believes that the detail of each note, from the intricate design features through to the iconography and unique 'waxy' stock "satisfy our idea of what worthy currency is."
Banknotes hold a lesson for all designers as a perfect example of meeting user requirements for utility and expectation. "The user must be able to use a banknote as an everyday object of payment, but in contrast must believe in its uniqueness and social significance," says Webb. "The challenge for a designer is to find the perfect balance of visual elements that will solve this design quandary."