The Royal Family
(L-R) Camilla, Duchess of Cornwall, Prince Charles, Prince of Wales, Queen Elizabeth II, Prince Philip, Duke of Edinburgh, Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge arrive for the annual evening reception for members of the Diplomatic Corps at Buckingham Palace on December 8, 2016 AFP/Getty

Kate Middleton took centre stage as she posed alongside the Queen and the most senior members of the royal family for an historic photo ahead of the annual Diplomatic Reception at Buckingham Palace.

The image of the 'magnificent six', includes the Queen and her husband the Duke of Edinburgh, the heir to the throne Prince Charles with his wife, the Duchess of Cornwall, and the future King and Queen, the Duke and Duchess of Cambridge.

It is the first time a photographer has been allowed to photograph the Royal Family at the event which is traditionally shrouded in secrecy. The Queen reportedly made an exception in honour of her 90th birthday year, capturing the unique group photo as they prepared to welcome more than a 1,000 guests to the palace.

The event which sees the royal family host the world's ambassadors is a highlight in the royal calendar and an occasion which calls for the most formal of attires.

For Kate it was a rare opportunity to wear the diamond and pearl tiara, one of the most famous tiaras in the royal jewellery collection. The Cambridge Lovers Knot was a favourite of Princess Diana's and a fitting adornment for the high-profile occasion.

And while the mother-of-two is a global style icon, she is also renowned for recycling her outfits. Looking regal in red she opted for the same Jenny Packham dress she wore to her first official state banquet last year.

The Queen and Camilla also wore tiaras from the Queen's personal collection, and The Royal Family Order of Queen Elizabeth II, an honour bestowed on female members of the British Royal Family by the monarch and worn on formal occasions.

The men's traditional attire included sashes and knee-high socks with garters bearing the Garter of the Order of the Garter insignia, the most senior and the oldest Order of British chivalry Mail Online reports. Dressed in his finery Prince William seemed a little apprehensive about his unusual get-up as he posed for the rare photo ahead of the event.

The glittering white tie Diplomatic Reception is the largest reception held at Buckingham Palace for the diplomatic community attended by ambassadors, high commissioners, around 600 foreign diplomats based in London and around 300 British diplomats and senior figures from commerce, education, broadcasting and the arts. The event reflects the important role the Queen plays in UK international relations.