See the sweet nickname Prince William and Kate use for each other

The Duke and Duchess of Cambridge are careful not to regularly indulge in public displays of affection. But though it's not the norm or expected of royals, Prince William has been known to place a tender hand on Kate's back or hug her closely at a celebration.

It's no surprise, then, that onlookers were thrilled to hear William and Kate call each other by their nickname "darling" at the Chelsea Flower Show on Monday (May 23), when the royals made their debut as a couple at the event.

The prince was overheard asking Kate if she could make her own poppy while they knelt to admire the 5,000 Poppies project – a stunning display of 300,000 knitted flowers laid out on the grounds of the Royal Hospital Chelsea.

TAP TO SEE FULL GALLERY William and Kate made their debut as a couple at the Chelsea Flower Show

One of the designers, Margaret Knight, told reporters: "William asked Kate, 'Could you make one of these, darling?'"

The Duchess said that she liked the "fluffy ones" made of felt and said "Well done, I'm so impressed with this" as she laid her own knitted poppy down.

"Could you make one of these, darling?" William asked his wife as they viewed a knitted poppy display

William and Kate, who were joined by Prince Harry at the flower show, then moved on to inspect the Support the Husqvarna Garden, which was shipped from Melbourne, Australia. Designer Mick Conway noted how the royals affectionately addressed each other.

LOOKING BACK ON CELEBS AND ROYALS AT THE CHELSEA FLOWER SHOW

"They seemed very interested in the garden," said Mick. "William in particular, he said, 'This for me is gold by far.' He also asked what this plant was (pointing to a Buxus) and Kate said to him, 'Darling, we've got that.'"

The couple was joined by Prince Harry

The royals also had the chance to view a flower – a pink and green Rossano Charlotte chrysanthemum – named after their little girl Princess Charlotte. It is being sold for the first two years through Waitrose with part of the proceeds going towards East Anglia's Children's Hospice, the charity of which Kate is patron.

William asked where they were available and joked, "You could always steal one off the exhibit!"

Kate replied: "Waitrose are selling them!"

Clearly in a jovial mood, the Prince asked Alison and John Peace from the Chrysanthemum Society if they could spell chrysanthemum. "I can't even say it," he laughed.

Kate asked, "Do you have a favourite? You don't have to be biased" while Prince Harry pointed at the centre of the display and joked, "What about the one that's in the middle?"

The trio were joining the Queen and other members of the royal family including Sophie Wessex, Princesses Beatrice and Eugenie and Princess Anne on the opening day of the flower show. The Queen, who is patron of the event, is a regular fixture alongside Prince Harry.

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