This sight would have been a treat for any passing motorist. It was the sight of Princess Diana, driving along the motorway with music blasting from her stereo and singing loudly, her two boys enthusiastically participating from behind the seats.

Moreover, the Royal pop group had an unlikely additional member – their Royal personal protection officer.

In a loving reflection on his mother’s character, the Duke of Cambridge vividly recreates the scene in which Princes William and Harry are being taken back to school by their mom.

The song of choice, rather aptly, was Tina Turner’s Simply the Best and it was deployed by Diana to raise the spirits of her children as they returned to boarding school.

William, 39, admits the happy memories are tinged with sadness as the ‘family moment’ is cut short as the school gates appear into view and he realises he must say goodbye. ‘When I was younger, Harry and I, we were at boarding school,’ says William, who began boarding at Ludgrove school in Berkshire when he was eight.

Princes William and Harry sang with Princess Diana to fight off their anxiety. Prince William and Princess Diana going back to Wetherby School, Notting Hill, London in 1992

Harry and Prince William sang together with Princess Diana in order to ease their anxiety. Prince William and Princess Diana returning to Wetherby School in Notting Hill, London, 1992

‘And my mother used to play all sorts of songs to while away the anxiety of going back to school. And one of the songs I massively remember and has stuck with me all this time, and I still, to this day, still quite enjoy secretly, is Tina Turner’s The Best [sic]It felt like a true family moment, sitting back in the seat and singing.

‘And my mother, she’d be driving along, singing at the top of her voice. And we’d even get the policeman in the car, he’d be occasionally singing along, as well.

‘You’d be singing and listening to the music right the way out into the gates of school, when they dropped you off.

‘And, and that’s when reality kind of sunk in that you really were going back to school because before that, you’re lost in songs. You’ll want to play it again just to keep that family moment going.

‘And when I listen to it now, it takes me back to those car rides and brings back lots of memories of my mother.’

Ken Wharfe, a former Royal personal protection officer told The Mail on Sunday: ¿They were such happy times. Yes, there were all the issues of the Royal marriage, but the Prince and Princess did their very best at that time to keep their children out of it, so they were largely oblivious and they had great fun with their mother'

Ken Wharfe, a former Royal personal protection officer told The Mail on Sunday: ‘They were such happy times. While there were issues surrounding the Royal Marriage, Prince and Princess tried to keep the children away from it. However, they did everything they could and were very oblivious. The kids had great fun and enjoyed their Mother’s company.

Ken Wharfe, an ex-royal personal protection officer, told The Mail Sunday night that he had been the singing cop mentioned by William. 

Mr Wharfe, 73, who now sings bass-baritone in the English Chamber Choir, said: ‘They were such happy times. There were many issues in the Royal wedding, but Prince and Princess tried their best to avoid them. They were mostly oblivious, and the children had great time with their mother.

‘The Princess loved Tina Turner and would put the CD on full blast in the car, sometimes in the green Jaguar XJS she had, or other cars, the CD always came with us.

‘She played Simply the Best all the time and some Cliff Richard.’

William also pays tribute his mother in the Time To Walk podcast by recalling the life lessons she instilled into him. Harry was taken by her to the homeless shelters from an early age.

William continued her work as the patron of Centrepoint.

‘My mother took me to a homeless shelter to meet people who were down on their luck and who had a very difficult time in life,’ he says.

‘She wanted to make sure that I understood that life happens very much outside of palace walls, and this is what’s going on. It’s the real world. And we sat there, and we listened.’