On 15th February, 1971, British currency underwent its biggest change in centuries, when the existing system (whereby pounds were divided into 20 shillings or 240 pennies) was retired.
The so-called '£sd' system - which had been in use since the Norman Conquest of 1066 - came to an end with the ringing in of decimalisation. This changeover was arguably the biggest overhaul of Britain's currency ever.
Aspects that would change the face of Britain's currency had been ongoing for a long time before the change took place, however. In fact, measures that would go on to influence our paper currency were being taken as far back as 118BC.
Despite coins being created as far back as 700BC, notes came about around 500 years later when the Chinese (running out of copper reserves to make their coins) cut deerskin which could be used in their place (bankofengland.com).
It wasn't until the 16th century that notes like those consumers of today would recognise came to the UK. They were introduced by goldsmiths, who would write receipts for the amount of coins they'd been given. Then, because goldsmiths were inherently trusted, these receipts became as good as the money they represented and were soon being traded by consumers as cash.
Around a century later, the Bank of England issued official banknotes to help raise money to fund a war against the French and the modern banknote was born - albeit a primitive version of the one we see today.
Today, British notes are made from a blend of cotton fibre and linen rag by a special paper manufacturer, which makes them more durable than traditional paper made from wood pulp. It works by breaking down cotton into individual strands with huge volumes of water, before these are then woven into a papery substance.
Once the paper has been manufactured, three different printing techniques are used to help make it more difficult for forgers to replicate. The majority of a note is printed using 'offset litho', which is used to produce high-quality, clearly-defined images. The raised print and Queen portrait are added using 'intaglio' so pressure can cause the rise. It is this method which also gives the notes their unique feel. Lastly, the cypher and serial numbers are added through a 'letterpressing' process.
These processes aren't replicated around the world, however and some countries have hugely different methods for creating their bank notes. Australia, New Zealand, Papua New Guinea, Romania, Brunei and Vietnam, for example, are among the 23 countries around the world to exclusively use polymer notes. Canada is currently in the changeover process (blueandgreentomorrow.com).
Notes of the future
Polymer notes are made from plastic that is said to last 2.5 times longer than paper (bankofcanada.ca). This is useful not only because it is more likely to stop notes from being damaged whilst in people's possession, but also has less of an environmental impact, as the bank has to replace worn notes less often.
These notes are also able to take more difficult-to-replicate security features, such as the new Canadian notes which have a transparent section containing both a metallic portrait and an image of a well-known building. The outline of a maple leaf elsewhere on the note is also transparent, to make replication that little bit more difficult still.
Back in Britain, however, the paper versus polymer debate looks set to be put off for quite a while - with the British Museum's 'Modern Money' curator, Tom Hockenhull, claiming that paper is "much more secure than it used to be" and now boasts "features that are extremely hard to counterfeit" (bbc.co.uk).
The issue has prompted much consternation, with debates raging over which notes - if any - should be trialled as a polymer. The £5 note is one that changes hands often, leading some to claim it would benefit from being more robust. The £50 note, on the other hand, is one that's used less frequently but would be more damaging if counterfeited on a large scale. The result was a mooted idea to trial the two notes as polymers, leaving the £10 and £20 unchanged until opinion is gauged.
As yet, even the first steps of this process haven't materialised - meaning that for the time being, notes look to remain in their current guise.
A number of measures - some old, some a little more recent - have been used to make consumers more confident in their ability to identify forgeries. They also provide a way for the Bank of England to make replication that little bit more difficult.
Firstly, some text on genuine notes has been raised, such as that across the top which reads 'Bank of England'. The effect is minimal and often overlooked but can still be felt by simply running a finger along it.
One of the most well-known security aspects is that of the metal thread. This - along with the Queen's profile watermark - is one that can be viewed quickly and easily by simply heading the note up to the light. Typically, the line will look intermittent, but will end as a full, unbroken line when held up to the light. Likewise, the Queen's profile will also appear in the large oval in the note's middle when held up to the light.
The Bank of England also uses its ability to print in incredibly fine detail with the use of microlettering. These tiny letters are just about visible (although some may need a microscope) underneath the Queen's head, albeit in different formations on each note variation. The letters will spell out the value of the note.
Consumers in possession of an ultra-violet light can also verify notes by holding them underneath. Authentic ones will look dull in colour, except for a number that becomes visible and correlates to the note's value. Furthermore, it should be easy to spot, being in a striking red and green pattern.
Whilst seen by many as a thoroughly modern institution, banknotes do go markedly further back than many realise. With all the technical advances being trialled across the world, there looks to be a great deal of life still in them yet.