Supermarket giant Tesco will unlock 100,000 of its coin-operated shopping trolleys after it failed to convert them in time for the circulation of the new £1.
The new, lighter and reportedly more secure 12-sided coin enters circulation on Tuesday, beginning a six-month transition period before the old "round pound" ceases to be legal tender.
Meanwhile, supermarkets such as Sainsbury's, Asda, Morrisons, Lidl and Aldi have said all of their trolleys have been updated ahead of the Tuesday deadline.
Local authorities are already coping with a surge in the number of abandoned trolleys, after a tax on plastic bags came into force that encouraged some shoppers to leave supermarkets with the carts.
Tesco said trolleys across “fewer than 200” of its shops will be unlocked from Tuesday as the store upgrades them to accept the new coin.
A Tesco spokesperson offered assurances that all trolleys would be upgraded by the time the new round pound ceases to be legal tender on 15 October.
“We're replacing the locks on our trolleys to accept old and new pound coins as well as existing trolley tokens," they said.
“As an interim measure we will unlock trolleys while this process is completed and we will continue to have colleagues on hand to attend trolleys in our stores, so our customers aren't affected by the changes.”
It recently emerged that the new £1 coin could pose problems for drivers, with an estimated one in ten parking meters not ready for the change.
Vending machine operators are also not prepared. Despite a £32m industry effort to upgrade Britain's vending machines, 15 per cent of them still unable to accept the new coins.
The Automatic Vending Association (AVA) said that with around half a million vending machines across the UK, ensuring all of them are upgraded is a “major operation”.
The body has estimated that all vending machines will be fully upgraded by the end of the transition period in October.
The new coin has been described as the most secure coin in the world, boasting high-tech features, including a hologram.
The coins have been made at the Royal Mint in Llantrisant, South Wales, at a rate of three million per day.
They have a gold-coloured outer ring and a silver-coloured inner ring and are based on the design of the old 12-sided threepenny bit, which went out of circulation in 1971.
It might take a few days or weeks for people to start seeing the new £1 coins turn up in their change as they gradually filter into general use.
The production of the new coins follows concerns about round pounds being vulnerable to sophisticated counterfeiters. Around one in every 30 £1 coins in people's change in recent years has been fake.
Press Association contributed to this report