Last-minute preparations are being made ahead of the introduction of the new 12-sided £1 coin.
The new coin, which arrives on Tuesday, has been described as the most secure coin in the world and boasts high-tech features, including a hologram.
But consumers craving a snack or trying to park may face confusion when they attempt to pay at coin-operated machines, as some will not immediately accept the new coin. They may find themselves rifling through their wallets for an old round pound.
Tesco trolleys across many of its stores will be unlocked as the supermarket giant performs upgrades so that they can accept the new coin.
A Tesco spokesman said last week that “fewer than 200” of its stores would be affected.
He said: “We will continue to have colleagues on hand to attend trolleys in our stores, so our customers aren’t affected by the changes.”
The old coin and the new coin will co-exist together for a period of around six months, until the round pound ceases to be legal tender on 15 October.
The new 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.
The Automatic Vending Association (AVA) estimates that when the new coin goes into circulation, around 85 per cent of vending machines will be able to accept the new £1 coin and all will still accept the old coin.
It said that with around half a million vending machines across the UK, ensuring all of them are upgraded would be a “major operation”.
The body has estimated that all vending machines will be fully upgraded by the end of the transition period on 15 October.
Jonathan Hart, chief executive of the AVA, said the upgrades needed for the new £1 coin would cost the vending industry an estimated £32 million.
He said: “We support the Royal Mint and the Treasury’s actions to protect the integrity of currency in the UK and reduce the level of fake coins in operation.”
A spokesman for the British Parking Association (BPA) said the majority of parking machines would be ready but some older machines may not be able to be upgraded and so new equipment may need to be bought.