The award, run by the Royal Forestry Society, aims to “inspire young people to learn about the benefit of trees and assist in woodland management in their local community”.

The Queen’s Green Canopy project will see members of the public plant trees in their communities to mark 70 years on the throne.

The two previous images of the Queen on horseback on the Royal Mint coins have included named horses known as personal favourites of Her Majesty.

All feature the Queen wearing a long skirt, military tunic, hat with plume and medals.

Mr Bergdahl said of his version: “I decided to differentiate the familiar equestrian portrait by including the royal garter taken from the Royal Coat of Arms.”

The new coin includes the motto of the Order of the Garter, “Honi soit qui mal y pense”, inscribed around the Queen.

The obverse design – the “tails” side – features the number 70 along with the Queen’s cypher.

The range of commemorative coins will cost between £7 to £385,200 for a limited edition of two 5kg gold proof £5,000 coins.

The £5 coin, issued in unlimited amounts for the general public, costs £10, while a platinum piedfort proof version costs £5,495.

‘Collected, cherished and passed down’

Clare Maclennan, the Royal Mint’s Divisional Director of Commemorative Coin, said: “The Platinum Jubilee is an historic occasion and one that is particularly special for The Royal Mint, as the original maker of British Coins for 1,100 years.

“In celebration of this landmark event, the official Platinum Jubilee collection, including the new 50p and traditional £5 crown, features a unique commemorative design on both sides of the coin.

“Designed by esteemed artists and made with original craftsmanship, Her Majesty’s Platinum Jubilee coins are enduring pieces of art that will be collected, cherished and passed down for generations.”

Chris Barker, Royal Mint Museum historian, said: “The Queen’s legacy on coins stretches the length of her momentous reign, with The Royal Mint striking five definitive portraits of Her Majesty on official UK coin and celebrating previous Jubilees.

“The 1977 Silver Jubilee crown was the first major UK commemorative coin produced at The Royal Mint’s Llantrisant home, after the minting in London ceased in 1975.

“Roughly 37 million coins were produced at that time, and thousands were gifted to children across the UK as a memento of the occasion.

“Today’s launch marks another significant milestone and The Royal Mint plays a proud part in the nationwide celebrations.”