The proposed new £1 coin will feature a design on the tails side selected by a public competition.

The Royal Mint has revealed plans to redesign the £1 coin, replacing the current round coin with a 12-sided design that it says is harder to counterfeit – but will require changes to vending and ticket machines and trollies that could cost over £15 to £20 million (according to The Telegraph).

The design is based on the old thruppenny bit, which went out of circulation in 1971. It features two different coloured metals – like the £2 coin – and uses the 'iSIS' security feature that the Mint says is based on anti-counterfeiting measures created for bank notes.

£1 coin design competition

While the front of the coin will have the Queen's Head, the Royal Mint says that it host a public design competition for the coin's tails side – in a similar fashion the competition it ran for the 50p coins released for the 2012 Olympics in London. No date has been set for the competition, but the Mint wants to coin to enter circulation in 2017.

In a document on the design process, the Mint says that the body charged with the design of the coin, The Royal Mint Advisory Committee (RMAC), will judge submitted designs on "how the design brief has been interpreted, standards of creativity, use of lettering, balance of overall composition and competence of draughtsmanship. Designs are also assessed for their suitability for translation onto a struck coin."

Despite the cost of implementing the new coin, the Royal Mint's proposal has the backing of the government. Chancellor George Osborne has released a statement saying that "after thirty years loyal service, the time is right to retire the current £1 coin, and replace it with the most secure coin in the world.

"With advances in technology making high value coins like the £1 ever more vulnerable to counterfeiters, it’s vital that we keep several paces ahead of the criminals to maintain the integrity of our currency. I am particularly pleased that the coin will take a giant leap into the future, using cutting edge British technology while at the same time, paying tribute to past in the 12-sided design of the iconic threpenny bit.”