Photo of Queen and Charles marks end of 90th birthday year

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A photograph of the Queen and the Prince of Wales has been released to mark the end of the monarch's 90th birthday year.

The previously unseen picture, taken by fashion photographer Nick Knight in May, shows the mother and son in the White Drawing Room at Windsor Castle before the final night of the Queen's celebrations at the Royal Windsor Horse Show.

Charles, wearing a black dinner jacket, appears to be smiling at the Queen - dressed in a sea green and dove grey brocade dress by Angela Kelly - who is looking directly ahead in the photograph.

The Queen turned 90 in April and marked the milestone with a series of events - including a private black tie banquet at Windsor Castle with her friends and loved ones.

In June, she celebrated her official birthday with a service of thanksgiving and a picnic on The Mall for 10,000 revellers.

She thanked well-wishers but said: "How I will feel if people are still singing Happy Birthday to me in December remains to be seen."

Mr Knight said: "It was a great pleasure and an honour to photograph Her Majesty The Queen and HRH The Prince of Wales at Windsor Castle.

"I wanted to create a modern portrait that showed warmth and humanity as well as strength and tradition."