While each individual coin of the realm was designed to be worth their face value only, some British coins are extremely valuable, due to mistakes made by the Royal Mint during production.
These rare coins are still in circulation, and could be in your purse right now.
Out of the estimated 28 billion coins in circulation, how many of us actually look at them?
You hand over a £10 note at the newsagents for your daily paper, and spend the change in the next shop you visit without ever examining the actual coins.
Yet some of those coins are worth way over their face value to collectors, and those who know that some dates or writings on coins are rare or unusual in some way.
What are these rare coins?
Some 2p coins dated 1993
When decimalisation was first introduced in the UK in 1971, all coins were imprinted the word 'new' in front of the word 'pence'.
This was to differentiate the monetary value with the old pence, or pennies.
There used to be 240 pence to the pound, and after decimalisation there was only 100 pence to the pound.
One new pence was equal to 2 or 3 old pence, and to ease the transition, the new coins were called 'New Pence'.
By 1982, 11 years after their introduction, it was decided that the public no longer need the word 'New' in front of 'Pence' on the coins.
And so, it was dropped.
But in 1983, the Royal Mint made a mistake and printed a number of 2p coins with the words "New Pence" printed on them.
The mistake was noticed and corrected, but a number of them were released into circulation.
If you find such a coin, it is advisable to take good care of it.
In 2009 London-based auctioneers were selling these 2p coins for between £500 - £700 ($800 - $1200) each. No doubt they are worth more now.
The 20p coin, showing new and old dates
20p coins with no printed date
In 2008, the Royal Mint made one of their regular 40 year design changes to British coinage.
If you look at the 20p pieces in your purse, you will see that pre-2008 coins had the date printed on the tail side, right in the middle of the coin.
The design change involved moving the date to the head side, in the writing around the perimeter of the coin.
A mistake was made where the date was not printed on either side.
An estimated 50,000 - 200,000 of these coins were released into circulation, making them the first coins printed without a date stamp since 1672, when Charles II was on the throne.
Once the mistake was noticed, a company called The London Mint Office, who (despite their name) have no connection at all to the Llantrisant, South Wales, Royal Mint, immediately offered a reward of £50 to anyone willing to exchange one of these coins.
In the days following, eBay was flooded with sellers of these 20p coins, the highest of which is reputed to have sold for £20,000 ($32,500).
Most easily reached a price of £250 ($400), but I'm sure those sellers must have felt sick when they saw one reach those dizzy heights.
Rare Coins Poll
Rare Mint Marks on Coins
It is best to keep an eye at all times on the coins in your possession.
Rare mint marks add substantially to their face value.
Sometimes errors are made in the striking of coins, and while most of those 'mistakes' are never released, the odd one sometimes slips through.
The error could be something glaring like the two examples above, and they may be mild, like extra marks on coins as they were being made.
Collectors also look out for these rare coins, and are generally willing to pay well over the face value in order to add these coins to their collections.
Richard Clarke on December 28, 2016:
I have an undated 20p coin which I will keep in the hope it increases in value in time.
I wonder if anyone can tell me if a £2.00 piece dated 2015 with the words Standing on the Shoulders of Giants on the rim looking from the tail side instead of the usual head side when reading 1t is worth anything more due to this fact?
gail on September 06, 2016:
i have a 2 pound coin 2014 the first world war , the writing around the edge is upside down also half the dots around the edge of the queen are missing , and the letter Y in the word "you "passes through the sleeve ov his coat. could this be worth anything thankyou
Doreen on October 28, 2015:
I have a few 2p coins with New Pence on the reverse but none have a date. How can I tell which are 1983 coins please?
KAFF on August 12, 2015:
I have 2 £1 Floral Emblem of Scotland coins 1 of them has the writing around the side upside down - anyone know if it is worth anything please
danny on April 08, 2015:
Just checked my change and found a 2 pound coin with world war 1 1914 - 2014 is it worth anything please
emmag06 on October 13, 2014:
Hi does anyone know whether a 2010 £2 coin with doubled lettering is rare or higher value? The words 'elizabeth' and 'def' are doubled on the £2 coin I have.
Blackspaniel1 on October 11, 2014:
Les kent on August 27, 2014:
As for finding a rare coin I have been very very lucky I have 8 so far, I collect all the opposite inscriptions on the £1 £2 & £5 coins and I found a unique £2 coin in one of my proof sets.
So they are out there.
Metal Detectorist (author) on August 25, 2014:
Google coin dealers in your area. They have specialist knowledge.
Twibfan on August 15, 2014:
I have found sealed rolls of 1971 copper coins which have never been in use.
They 2p's, 1p's & 1/2p's.
Does anyone know if they would be worth anything more than the face value please?
Metal Detectorist (author) on September 21, 2012:
Thanks! I'll need to find out more about rare US or Canadian coins, that would be interesting too :)
The Reminder from Canada on September 20, 2012:
Great hub and useful info!
Metal Detectorist (author) on September 20, 2012:
I had loads of 20p pieces myself, but they all had a date! I'm keeping a close eye on the 2p pieces I keep finding on the local beaches, once I clean the gunge off.
Ethan Green on September 20, 2012:
Same here; time to check my coin jar. Imagine that - finding a seemingly worthless coin and discovering a fortune:-)
SkeetyD on September 20, 2012:
Great hub! Very interesting subject.
Kim Kennedy from uk on September 20, 2012:
Ooh, I'm off to check my change right now, so fingers crossed! Thanks for the info.