Queen Elizabeth II sat for her first official portrait as the reigning monarch 70 years ago

In an instant, Queen Elizabeth II transformed from a grieving princess into England's reigning monarch..

Her Majesty sat for her first official portraits 70 years ago, the iconic photos used as the basis for the Queen's image on coins, banknotes, and stamps all over the United Kingdom.

The portraits were taken exactly 20 days after the Queen's father King George VI died on February 6, 1952, propelling her into the throne at the tender age of 25.

READ MORE: Queen Elizabeth's Platinum Jubilee: Everything you need to know about celebrations for monarch's 70 years on the throne

READ MORE: 'Princess Mary and Kate: Could this be the warmest, and most sincere royal friendship?'

Kensington Palace marked the milestone date by sharing the poignant black-and-white portrait onto the official royal Instagram.

"On this day 70 years ago, just twenty days after her accession to the throne, The Queen sat for her first official portraits as Sovereign," the statement read.

"These iconic photographs were taken by Dorothy Wilding to produce portraits to use as the basis for The Queen's image on new coins, banknotes and stamps, as well as providing the official portrait of Her Majesty which was sent to every British embassy throughout the world."

The statement continued: "As part of the #PlatinumJubilee celebrations this year, @royalcollectiontrust are staging a special exhibition in the State Rooms at Buckingham Palace that will feature a display looking at The Queen's Accession to the throne in February 1952."

READ MORE: Row over royal documentary could see 'a withdrawal of co-operation' during Queen's Platinum Jubilee

The re-release of the Queen's first-ever portraits is part of the Platinum Jubilee celebration, which will mark 70 years of service.

The Queen will become the first British monarch to celebrate a Platinum Jubilee.

When King George VI passed away in his sleep in 1952, the Queen was in Kenya at the time and also became the first sovereign in over 200 years to accede the throne while overseas.

Following the news of her father's death, Queen Elizabeth II flew back to Britain, where she was greeted by Prime Minister Winston Churchill at the airport.

READ MORE: 'After her COVID-19 diagnosis, the Queen is now able to relate to her fellow Brits like never before'

Her accession occurred in 1952, while the official Coronation took place in Westminster Abbey on June 2, 1953, when the Queen was aged 27.

Queen Elizabeth's Platinum Jubilee celebration is set to be a spectacle across the United Kingdom.

Buckingham Palace announced a series of royal tours for senior members of the royal family, on behalf of Her Majesty, to different parts of the Commonwealth.

Ballots are also open for 10,000 tickets to people in the UK for the Queen's Platinum Jubilee concert, on June 4.