The royal princes William and Harry have had all but one significant scene of them cut out of Diana, a new film about their late mother’s torrid romance with heart surgeon Hasnat Khan.

The princes, played by actors Laurence Belcher (William) and Harry Holland (Harry), are shown briefly with Diana, played by Naomi Watts.

She hugs them, ushers them onto a waiting helicopter bound for Balmoral, and says she’ll see them in five weeks’ time.

 Diana, the movie, is first and foremost a love story, about an extraordinary woman in an extraordinary situation, who falls for a man with no social pretensions, renowned heart surgeon Dr Hasnat Khan

The poignancy of the moment becomes apparent later, when you realise that will be the last time they see her.

Director Oliver Hirschbiegel explained that other shots featuring the princes were dropped ‘because it never felt right to have them in the film’.

‘Everyone knew she was a brilliant mother and loved her boys to death,’ he said.

Both he and producers Robert Bernstein and Douglas Rae insisted footage of the princes — including an imagined scene of a game of cricket involving the boys, Diana and Hasnat — was removed for artistic reasons, not because of any outside pressure.

I am the first critic in the world to have seen a version of the film (it’s still being finished), and can reveal that Diana, the movie, is first and foremost a love story, about an extraordinary woman in an extraordinary situation, who falls for a man with no social pretensions, renowned heart surgeon Dr Hasnat Khan.

But it’s also about an iconic royal who felt rejected by those closest to her. ‘Your mother leaves you; your father marries a woman who, in your eyes, is just awful; your husband had a mistress all through your marriage. She had this lifelong longing for love,’ Hirschbiegel said.

Actress Nomi Watts stars in the Diana film, focusing on the last two years of her life and in particular her relationship with Dr. Hasnat KhanIt¿s a great picture about a deep, spiritual love affair between a lonely woman and a man who mends busted hearts

‘She finally got this true, passionate love from this heart surgeon, this Muslim man.’

Hirschbiegel, who directed the acclaimed German film Downfall, told me he knew what he was walking into when he accepted the project.

The first thing he insisted on was casting top-flight actors and getting a script that wasn’t full of hogwash. He also didn’t want to use any real-life footage. Rather, he recreates key scenes, such as Diana’s famous interview with Martin Bashir, from the last two years of her life.

It’s a great picture about a deep, spiritual love affair between a lonely woman and a man who mends busted hearts.

It works because it has been directed with incredible sensitivity by Hirschbiegel — and because of the performances by Watts and Naveen Andrews (as Hasnat).

Of course, it helps to have the services of proper actors rather than mere lookalikes. Neither Watts nor Andrews is a mirror image of the character they portray. But they capture the essence of the turbulent princess and the clever surgeon, and their topsy-turvy love.

Diana likes that he heals people; he’s intrigued by her.

But how does he contact her? ‘I’m like most people,’ she tells him. ‘I’ve got a mobile. In fact,’ she corrects herself, ‘I’m not like most people. I’ve got four.’

‘One will do,’ the good doctor responds. Diana suggests he could ‘pop around the corner and have supper with me’ after he finishes duties at the hospital, an offer he takes her up on.