Princess Diana loved dressing princes in '˜bizarre costumes'

William and Harry dressed as policemen. Picture: PA

Proud mum Diana appeared to like nothing better than putting the Duke of Cambridge and Prince Harry in matching outfits or themed clothes when they were boys – which to this day has left the royal brothers wondering why.

In the picture, William and Harry are dressed as policemen with toy helmets, ties and utility belts with walkie-talkies. Harry has a confident pose with his hands on his hips while his brother squints at the photographer who is thought to be their mother.

In the documentary, which is to be broadcast today, Harry said: “One thing I would love to ask her now because I genuinely think that she got satisfaction out of dressing myself and William up in the most bizarre outfits, normally matching.

“It was weird shorts and little sort of shiny shoes with the old clip on. Looking back at the photos it just makes me laugh – I just think: ‘How could you do that to us?’

“And then funnily enough, we got to the age when William would turn round and go: ‘Oh, this is ridiculous, you know, I’m the older brother, why do I have to be dressed the same as him?’

“And I’m sort of sitting there going: ‘Hang on a second, if you’re going to dress differently, I’m not going to be the only person dressed like this – this is just ridiculous.’”

Despite the embarrassment Harry felt, he joked that he will follow his mother’s lead when it comes to clothing his own children one day.

He said, laughing: “So I like to think that she had great fun in dressing us up. I’m sure that wasn’t it, but I sure as hell am going to dress my kids up the same way.”

A second photograph, also from Diana’s personal album and discovered by her sons recently, has been published for the first time and shows the princess and Harry sitting on the deck of the Royal Yacht Britannia.

Harry looks to be around six to nine months old, but his older brother William, who would only have been aged around three years or less at the time, is credited with taking the picture. Diana, dressed in a blouse and trousers and wearing sunglasses, cradles Harry in while they sit and play with some toys.

The Duke of Cambridge has admitted speaking openly about his mother for the new documentary about her life was “daunting” at first but the process has been a “healing” one.

William described the 90-minute programme as a “tribute” to Diana, Princess of Wales that will remind the public – especially those too young to remember her – of the “warmth” and “humour” of the global figure.

But the ITV documentary will be the first and last time he, and Prince Harry, will speak candidly about their mother.

“We won’t be doing this again – we won’t speak as openly or publicly about her again, because we feel hopefully this film will provide the other side from close family friends you might not have heard before, from those who knew her best and from those who want to protect her memory, and want to remind people of the person that she was.”

l The documentary, Diana, Our Mother: Her Life and Legacy will be screened on  ITV today at 9pm.