Old £1 coins will be worthless in a month and taken out of circulation

Round £1 coins are set to be melted down and used to produce the 12-sided version

Round £1 coins will no longer be spendable from October (Getty Images Europe)

People across the UK are being urged to spend or bank their old £1 coins before they become worthless in one month’s time.

The new 12-sided coin entered circulation across the UK in March and shops, restaurants and other business have been told to stop accepting the traditional round ones on 15 October.

“Our message is clear: if you have a round one pound coin sitting at home or in your wallet, you need to spend it or return it to your bank before 15 October,” Baroness Neville-Rolfe, commercial secretary to the Treasury, said earlier this year.

Martin Lewis from the MoneySavingExpert website warned in March that it’s “all too easy to squirrel money away in piggypanks and forget about it”.

Back then the Government estimated that around a third of the £1.3bn worth of coins stored in piggy banks or savings jars around the UK were denominated in the old £1 coins.

Some of the old coins that are being returned by the public will be melted down and used to make the 12-sided version.

The new coin, which was announced in the 2014 Budget, has been described by the Royal Mint as “the most secure coin in the world”, but the transition has had glitches.

Last month experts warned that companies are sending back the new 12-sided coins instead of the old ones by mistake.

MP Andrew Jones, exchequer secretary to the Treasury, said that there had been a “fantastic effort from both the public and businesses in returning more than one billion old round pounds” but that “businesses must remain vigilant when returning coins.”

The 12-sided coin has a number of features that make it considerably more difficult to fake. It is made from two metals, the outer gold ring of nickel-brass and the inner section of nickel-plated alloy.