When they stepped onto the red carpet for the premiere of Mandela: Long Walk To Freedom last night, Kate Middleton and Prince William looked happy, relaxed and glamorous.
"We were just reminded what an extraordinary and inspiring man Nelson Mandela was"
But, when they stepped out afterwards, it was a completely different story. For, shortly before reaching the end of the film which documented the life and times of Nelson Mandela, the Duke and Duchess had been discreetly informed by an aide that Nelson Mandela had died.
Stepping out of the Odeon Leicester Square, Prince William said: "I just wanted to say it's extremely sad and tragic news.
"We were just reminded what an extraordinary and inspiring man Nelson Mandela was. My thoughts and prayers are with him and his family. It's very sad."
The royal couple looked ashen-faced as they walked down the stairs into the foyer. Shortly after they left, shocked members of the audience began emerging from the cinema, in silence at first.
But none were so overwhelmed as Mandela's daughter Zinzi, who had also been present at the film screening.
Speaking before the movie, Ms Mandela had told reporters that her father was doing well:
"My father is fine. He's 95 years old and he is pretty frail. We are hoping to see more of him."
She had appeared, like William and Catherine, relaxed and in good spirits while walking the red carpet outside, but later seemed to be overcome.
Her publicist waved away reporters, prompting speculation that she had received word that her father was close to death.
She then went into the cinema but, just moments later, was seen looking tearful and flustered as an aide helped her to sit down. But, in an enormous act of courage, she insisted that the film still went ahead - and fellow viewers were not informed until after the credits that the man who helped to end apartheid in South Africa had passed away peacefully at home.
Idris Elba, who is tipped for an Oscar for his portrayal of the great man, said in a statement: "What an honour it was to step into the shoes of Nelson Mandela and portray a man who defied odds, broke down barriers, and championed human rights before the eyes of the world. My thoughts and prayers are with his family."
And Harvey Weinstein - co-chairman of the studio that made Long Walk to Freedom - also expressed his sorrow.
"One of the privileges of making movies is having the opportunity to immortalise those who have made a profound impact on humanity,' he said.
"We count ourselves unspeakably fortunate to have been immersed in Nelson Mandela's story and legacy"
"We count ourselves unspeakably fortunate to have been immersed in Nelson Mandela's story and legacy.
"It's been an honour to have been granted such proximity to a man who will go down as one of history's greatest freedom fighters and advocates for justice.
"I have had the privilege of spending time with President Mandela and I can say his sense of humour was as great as his optimism. We are deeply saddened by his loss; our hearts go out to his family and the entire South African nation."
The world continues to mourn Nelson Mandela.