Paper £20 and £50 sterling notes have had their legal tender status withdrawn by the Bank of England.

From today, polymer £20 and £50 notes will be the only versions accepted as payment by businesses.

It brings an end to over 320 years of paper money in Britain.

The withdrawal includes the paper £20 notes issued by Bank of Ireland (UK), AIB Group (UK), and Ulster Bank in Northern Ireland.

Polymer banknotes were first introduced by the Bank of England in 2016. The £5 note featuring Winston Churchill was the first to be switched.

New £20 notes featuring the artist JMW Turner were issued in February 2020, followed by the polymer £50 banknote featuring the Bletchley Park codebreaker and scientist Alan Turing in June 2021.

Although the majority of paper £20 and £50 banknotes in circulation have been replaced with new polymer versions, there are still over £5 billion worth of paper £20 featuring the economist Adam Smith, and nearly £6 billion worth of paper £50 banknotes featuring the engineers Boulton and Watt, in circulation.

That is more than 250 million individual £20 banknotes, and more than 110 million paper £50 banknotes.

There is no deadline for exchanging the withdrawn paper notes but because they will no longer be accepted in shops, there has been rush to exchange them in the UK, with the Bank of England warning people to expect long queues at its headquarters at Threadneedle Street, London.

The Bank of England is advising holders of paper notes of their options.

Consumers with a UK bank account or Post Office account, will be able to deposit paper notes.

A limited number of Post Office branches in the UK will exchange withdrawn paper banknotes, or withdrawn banknotes can be exchanged with the Bank of England, including by post.

The Bank has moved to reassure holders of paper banks notes outside of the UK that they will not be left with a worthless currency.

"All genuine Bank of England notes that have been withdrawn from circulation retain their face value for all time and can be exchanged with the Bank of England in London."

A spokesperson for the Bank of England told RTÉ News that the bank does not have facilities overseas for people to return banknotes.

"People living in the Republic of Ireland can of course post their notes in to the Bank of England, or wait until they next come to England," they said.

"There is no time limit on returning these paper banknotes, either with us, or at participating post office branches."

A postal exchange form is available on the Bank of England's website. It should be sent with the banknotes and photocopies of ID for exchange to Department NEX, Bank of England, Threadneedle Street, London EC2R 8AH.

For payments to Irish bank accounts, people must provide the BIC/SWIFT Code and IBAN or account number.

The Bank can only pay into accounts that accept sterling. It says all payments are sent via SWIFT transfer. It does not charge for this service, but the customer's bank may charge them.

"If we are unable to make an electronic payment, we will send a sterling cheque payable to you," the spokesperson said.

The Bank of England does not send banknotes overseas.

In the meantime, the Bank said all polymer banknotes carrying a portrait of HM Queen Elizabeth II remain legal tender, and the public can continue to use these as normal.

"A further announcement regarding existing Bank of England banknotes will be made once the period of Royal mourning has been observed," it said.

It is expected that Britain's banknotes will in time be replaced with notes featuring the head of King Charles in a process that is expected to take at least two years.