Prince George of Cambridge's first birthday is to be marked with a commemorative £5 coin.

The Duke and Duchess of Cambridge's young son is the first member of the royal family to have his first birthday honoured with a new UK coin.

William and Kate, along with George's great-grandmother the Queen and Chancellor George Osborne approved the design of the sterling silver piece, which bears the heraldic royal arms and the year 2014.

Third in line to the throne and future king George, who was photographed walking with the help of his mother and playing with a football at a polo match in Cirencester at the weekend, turns one on July 22.

Shane Bissett, director of commemorative coin and bullion at the Royal Mint, said: "As Prince George of Cambridge reaches the significant milestone of turning one year old, we felt there could be no more fitting design to mark the first birthday of our future king than the royal arms - the arms of the monarch - minted in honour of the future heir to the throne.

"The choice of a silver coin is significant too as the precious metal is closely associated with newborn babies, as crossing the palm of a newborn baby with silver is a way to wish them wealth and good health throughout their life, whilst the £5 coin is a favourite for royal celebrations."

There will be a limited mintage of 7,500 of the birthday coins, which will cost £80 each.

The heraldic royal arms - which incorporates the four quarterings of the royal arms each contained in a shield, as well as a rose, thistle, leek, a sprig of shamrock and a crown - was originally created for the Queen and was last used on a coin struck for the British Exhibition in New York in 1960.

Both George's birth and his christening were marked with commemorative coins.

:: The £5 birthday coin will be available via www.royalmint.com and is priced at £80.