New £1 coin: The 12-sided one pound comes in to circulation and becomes legal tender

The round pound will still be accepted as legal tender alongside the new coin for just over six months

The new £1 coin is being phased into circulation (PA)

A new 12-sided £1 coin is entering circulation on Tuesday, marking the first major change to its design in more than 30 years.

The old round coin is being phased out after first entering British pockets in 1983 when it replaced the pound note.

However, after almost 34 years in circulation, the current £1 coin has become increasingly vulnerable to sophisticated counterfeiters. An estimated one in 30 pound coins are fake, according to the Royal Mint.

The new coin, which the Royal Mint has been described as “the most secure” in the world, has a bi-metallic structure with a gold-coloured outer ring and a silver-coloured inner ring.

It also boasts new security features, which include a hologram-like image that changes from a £ symbol to the number one when the coin is seen from different angles. Around 1.5 billion of the new coins will be struck.

The round pound will still be accepted as legal tender alongside the new coin for just over six months, until October 15. By then, British customers will have had to either have spent or banked the old coins.

Ministers last month reminded the public of the importance of all old coins being returned before the date when they lose their legal tender status.

“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.

Some banks and building societies said they will accept the old £1 coin after the October deadline, but only from their own customers, according to Steve Nowottny from MoneySavingExpert.com.

Concerns have also been raised over whether coin-operated machines, such as vending machines, will be ready to accept the new coin.

The cost of changing over machine mechanisms for small and medium-sized businesses (SME) has previously been described as a burden too far.

Clive Lewis, head of enterprise at the Institute of Chartered Accountants in England and Wales, last year said: "The financial hit SMEs will have to take in preparing for the new pound coin will divert attention away from running their businesses and dealing with the economic consequences of Brexit."

Last week, major providers including Southern Rail, Virgin East Coast and Transport for London said their machines would not be ready by Tuesday, prompting concerns that travel chaos could ensue.

Supermarket giant Tesco also announced last week that it 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. A spokesman for the supermarket on Friday said that "fewer than 200" of its stores will be affect.