Time to check your wallet! New King Charles Bank of England notes could be worth a fortune - and some are already for sale on eBay for triple their face value

If you already have your hands on the new bank notes featuring King Charles III, it may be in your interest to hold on to them, as they could be sold for a fortune.

The new notes entered circulation for the first time on Tuesday and already members of the public have started flogging them on eBay for triple their face value.

Each £5, £10, £20 and £50 note featuring the King contains an individual prefix and serial number to identify and date it with a four digit prefix. For each prefix, there are 999,000 notes printed, from 000001 to 999000.

Collectors are therefore on the hunt for notes with exceptionally low serial numbers, as these were the first printed by the Bank of England.

The Bank of England confirmed with This is Money that the first printed serial numbers are - CA 01 000001 (£5), HB 01 000001 (£10), EH 01 000001 (£20) and AJ 01 000001 (£50).

If you come into possession of a note featuring one of these prefixes, with an early serial number, you may find it is worth far more than its face value.

The Bank of England cannot confirm if the CA01, HB01, EH01 or AJ01 notes have entered circulation yet, but it is likely they will work their way into circulation in the coming weeks and months. 

Keen collectors queued outside the Bank of England on Wednesday morning to swap their old money featuring the late Queen Elizabeth II for new ones.

To get any serial number below 20 is exceptionally rare and none have been placed for sale online as of yet.

But already one King Charles £50 note, with the serial number AJ02 468341, is being sold online for £150.

Banknote specialists have also claimed notes which have serial numbers matching collectors' birthdays or those which have some relevance to the design of the note itself will be extremely coveted.

Olivia Collier, Banknote Specialist at Spink & Son said: 'There is a particular interest in notes which carry the number eight in their serial number from buyers in China and Japan. It's not just a domestic audience the bank notes garner.

'There is a harmony some collectors enjoy in finding notes with certain round numbers.'

Collectors and the general public can also get their hands on the new bank notes at a charity auction hosted by Spink & Son on behalf of the Bank of England.

In 2016, the first £5 Churchill note available - AA01 000017 - sold at auction for a huge £4,150.

For this very reason, more than a third of Britons - equivalent to around 20million adults - intend to keep their first King Charles note as a historical memento or in case it becomes collectable, an exclusive report from Coventry Building Society revealed.

Of 2,000 Britons Coventry asked, 15 per cent said they will hold onto the new notes when they get their hands on them to sell on eBay or at an auction for more money in the future, especially if they have an early serial number.

The auction for the new notes will take place on June 13 for a lot of 122 £5 notes, followed by an auction for £10 notes on June 27.

The £20 and £50 pound note auctions will take place on July 11 and July 25 respectively.

Auctioneers Spink & Son told MailOnline's This is Money that the lowest serial number available will be unmatched by anything they have previously offered in over 20 years of hosting charity auctions on behalf of the Bank of England.

Arnas Savickas, head of banknotes at Spink & Son, said: 'Depending on the serial number of the note - it's reasonable to assume that the lowest serial number of a £5 could fetch between £250 to £500, while £10 and £20 notes could go for £500 and £1,000 respectively. A £50 then could go for several thousand pounds.

'It's not impossible that outside of the auction, someone could find notes with a serial number within the first million.

'Outside of the auction, someone could potentially find a note with a serial number as low as six figures - you could probably get one with 100000.'