In a 2020 BBC radio interview during lockdown, the then Duchess of Cornwall extolled the virtues of dressing down during the lockdown period.

“I’ve been very, very happy with my jeans,” Camilla said. “It will be very hard to get out of them again. I think you get into a sort of way of life, don’t you?”

Photographs of Camilla at Clarence House for the interview show someone relaxed, with a loose blazer and feminine white shirt, not afraid of the odd crease.

The lesson for Kate: Casual dressing is a mood and a mindset.

Camilla Tip No. 2: Let the jewels do the work.

There are times when Kate leans into sparkle at the risk of falling in, such as the bedazzled Jenny Packham cape dress worn at the South African state dinner at Buckingham Palace in November and a green sequin Jenny Packham dress worn in Pakistan in 2021, but it’s time to dim the dress wattage.

Any celebrity can dress like a disco ball, but Camilla understands that it’s access to the crown jewels that set the Windsors apart from the Beckhams and Beyonce. At the South African state dinner in November and diplomatic corps dinner this month, Camilla’s dress was cut to accentuate the sapphire tiara, necklace and earrings that once belonged to Princess Louise of Belgium.

At the banquet in…