At 19M in the north of Paris he met six graduates of an embroidery course run jointly with Chanel and the Prince's Foundation who had created an embroidery inspired by his garden at Highgrove.
Eliza Kate Gomersall, 23, from Hildenborough, Kent talked him through her embroidery work, which was inspired by the Stumpery at the King's Gloucestershire residence as well as Japanese art.
Looking at her sketches, the King, himself an accomplished painter, asked: "Are these all done in watercolour? Absolutely brilliant."
She said afterwards: "He was really enthusiastic and interested in keeping this craft alive and keeping it current."
Elsa Searle-Vincent, 25, from Exeter, told the monarch how her work was based on a moss-covered fountain in his garden.
"What's fascinating about it," he replied, "Is how many species there are, and the extraordinary colours – the emeralds."
Another graduate told the King her work was based on the sunlight on the apple trees in the kitchen garden at Highgrove.
Earlier he and the Queen were introduced to the graduates of the six-month course as they sat around a long table working on embroidery making up a giant meadow-design.
"Do you think it's improved your skills?" asked the monarch. Told it had, he asked: "But then having done that, what to do next? Hopefully more of this!"
The King, who was joined on the visit by foreign secretary James Cleverly, spoke of the importance of nurturing traditional skills in the UK "to try and start building domestic capability".
Walking through to the Maison Lesage tweed workshop, the Queen examined a wall full of tweed samples, at which point Brigitte Macron urged her: "Choose one, Your Majesty."
The Queen replied: "All of them!"
Inside the workshop she was invited to have a go at weaving. As she sat down at the loom she said: "This could be a terrible mistake!"
The Queen looked a little nervous, prompting Macron to say: "Your Majesty, I am with you."
"You can help!" replied Camilla. But after the Queen had a tentative go, Macron told her: "Perfect! You did it."
The Queen joked: "It's obviously the next job for me."
As the King - who had a separate tour - crossed the courtyard of the 19M building in the pouring rain, he was given rapturous applause by the 600 employees who had come out on to the balconies to watch him below.
Back under cover, His Majesty was introduced to the ethical fashion designer Carla Fernandez, whose Mexican art-inspired work is on display at the centre and who had flown in from Mexico especially for the visit.
"Is it going well?" he asked her. "And am I going to get a glimpse?"
He was presented with a gift of local honey from the Aubervilliers suburb before moving on to meet local children making milagritos, jewelled Mexican good luck charms.
As he approached the table where they were working, Nathalie Abscheidt, a jeweller with Goossens running the workshop, asked if he would like to have a go himself.
"Who, me?" he laughed. "Yes, you!" she said.
Encouraged to sit down and add some gem stickers to a heart-shaped piece, he opted for a yellow one, told it would "bring happiness".
He giggled as he was applauded and told "bravo" for his efforts before turning to chat to some of the children taking part in French.
"He loved the fact that he was doing the workshop at the same time as the children," said Abscheidt.
Before leaving, the royal couple were presented with embroidered handkerchiefs bearing their cyphers and an embroidered artwork depicting the wrought iron gate overlooking the Sundial Garden at Highgrove.
The King joked, modestly: "There are much better French gardens."
Speaking after the visit, Hubert Barrere, creative director of Maison Lesage, hailed the monarch as "a visionary", saying: "It's a historic moment for us and a great moment to receive the King and Queen.
"Your King is a visionary man. When he decided to create the Prince’s Foundation in the 1970s, nobody imagined the problems of today – not just in terms of [craft] know how, but also the ecological problems.
"He’s not snobbish and a very interesting guy. He took time with the students and was very open minded. It’s good to have a king with an open-minded mentality - he’s a man of today."
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