The colourful homemade card was created by the Queen’s great-grandchildren Prince George, seven, Princess Charlotte, five, and Prince Louis, two. It is emblazoned with the number 73 that pops out from the front of the card.
The photograph released on Thursday night ahead of their anniversary on Friday shows the Queen and Duke of Edinburgh sitting on a sofa in Windsor Castle’s Oak Room and reading the special message from future king George and his siblings.
The Queen is wearing a pale blue double wool crepe dress by Stewart Parvin and a chrysanthemum brooch made from sapphires and diamonds set in platinum, while Philip wears a blazer, shirt, tie and trousers.
The picture, taken by Chris Jackson from Getty Images, also shows a small pile of anniversary cards and letters sent by well-wishers on a nearby table.
The Queen, 94, was a 21-year-old princess when she married the Lieutenant Philip Mountbatten at Westminster Abbey on November 20 1947.
Their enduring relationship has lasted the longest of any British sovereign and Philip has been at the Queen’s side throughout the decades, supporting her as she devoted herself to her role as head of state.
The Queen and the Duke, who has now retired from public duties, are spending the lockdown in England isolating at Windsor Castle, and anniversary celebrations are expected to be low-key.
There is no traditional gift, jewel or colour associated with 73rd wedding anniversaries in the UK.
READ MORE: Philip feared Queen ‘may not take to one aspect of marrying him’
Their long marriage is seen as a key source of stability within the monarchy.
Together they have celebrated the silver, golden and diamond jubilees of the Queen’s reign, and faced ups and downs over the years including the breakdown of three of their four children’s marriages, and the backlash which followed the death of Diana, Princess of Wales.
The past year has also been a tumultuous one. Royal events moved online during the first national lockdown with the Queen holding virtual engagements via video calls and meetings by phone.
And in the spring, the Duke and Duchess of Sussex stepped down as working royals for financial freedom and now live in California after signing a lucrative Netflix deal and appear poised to announce projects through their charitable body Archewell.
On their golden wedding anniversary in 1997, the Queen paid a touching tribute to her husband, saying: “He has, quite simply, been my strength and stay all these years.”
Philip used the occasion to praise the Queen for her abundance of tolerance.
He said: “I think the main lesson that we have learnt is that tolerance is the one essential ingredient of any happy marriage.”