Prince George at Princess Charlotte's christening
Prince George at Princess Charlotte's christeningWPA Pool/Getty

When most people hit a birthday milestone they celebrate by looking back at all that they have achieved, but Queen Elizabeth II is choosing to look forward. The record-breaking monarch has marked her forthcoming 90th birthday by posing with the new generation of Windsors – her great grandchildren Prince George and Princess Charlotte.

According to People magazine, a new family photo featuring her royal highness, the future King and possibly the future queen of England will soon be released. Although little details have been revealed about the soon-to-be iconic image, the photo session is said to have taken place at Windsor Castle at the end of an Easter holiday weekend with famed photographer Annie Leibovitz tasked with getting the trio's best angles. She was the same person that photographed the Queen during her 2007 state visit in the U.S.

Prince George and Prince Charlotte
Prince George and Prince CharlotteHandout/Getty

Although proud parents Kate Middleton and Prince William are noticeable absent from this picture, the site says that they were present at the shoot and were fine with being behind the camera for a change.

A palace insider told People that the birthday portrait with the young children was a "lovely way to mark a remarkable 90th birthday and added that Queen Elizabeth II "loves her great-grandchildren" and has been "very proud of them." While an expected release date was not disclosed, it is widely speculated that 21 April – the Queen's birthday- will be the big unveiling.

George and Charlotte are no strangers to the camera having posed for an array of official snaps. In June 2015, the first image of the royal siblings, taken by the duchess at Anmer Hall, was released and showed little girl being held tenderly by her older brother. In March this year Press Association's veteran royal photographer John Stillwell captured the pair as they joined their parents for a family ski trip to the French Alps.