About £7.2bn in old banknotes has not been cashed in across the UK, even though the paper £20 and £50 stopped being legal tender in October 2022.

Paper banknotes have been replaced with plastic notes with a series of security features.

The Bank of England said the withdrawn banknotes could still be deposited or exchanged.

There are also 76 million old £1 coins that have not been returned, according to the Royal Mint.

Details of the cash still in circulation or hiding in homes was revealed in Freedom of Information requests by BBC Wales.

The Bank of England said 395 million paper banknotes remained in circulation:

• 110 million £5 notes
• 62 million £10 notes
• 171 million £20 notes
• 52 million £50 notes

Paper £5 notes were withdrawn in May 2017, the paper £10 notes in March 2018 and paper £20 and £50 notes on 30 September 2022.

In addition to the paper cash, the Royal Mint, which is based in Llantrisant, Rhondda Cynon Taf, said about 76 million old style £1 coins had not been returned.

However, about 11 million have been returned over the past year.

Out of the 1.6 billion that have been returned, about 1.8 million were counterfeit.

The round £1 coin was replaced by the 12-sided version in October 2017. The old style coin can still be deposited at the Post Office but cannot be spent.

According to the Royal Mint, which is owned by the UK Treasury, about 138 million round £1 coins have been melted down to make some of the new ones.

The polymer £50 note featuring the portrait of wartime codebreaker and computer pioneer Alan Turing entered circulation on 23 June 2021, meaning the Bank of England’s entire collection of currently-printed banknotes is made of plastic.

While the paper notes are no longer legal tender, a spokeswoman said “all genuine Bank of England banknotes that have been withdrawn from circulation retain their face value. There is no expiry on the period in which we will exchange banknotes”.

They can be returned to some banks and some post offices, but the latter will only exchange a maximum of £300.

People can also post old notes to the Bank of England in the City of London to be paid into a bank account, by cheque or, “if you live in the UK and the amount is under £300”, swapped for new-style polymer ones.

Old notes can also be taken there in person but the bank warned that “our counter can get very busy”.

The use of cash fell sharply during the coronavirus pandemic as lockdowns reduced options for spending, and this accelerated a downward trend for the use of notes and coins.

However, cash still accounted for 12% of all payments in 2023, according to the latest figures by banking trade body UK Finance, making it the second most-popular way to pay after debit cards.