Kate was given a guided tour of family-run AW Hainsworth in Yorkshire and was said to have been "fascinated by some of the traditional processes" at the textile mill.

The company, based in Pudsey, makes textiles for a range of clients, from fashion houses like Gucci and woven felt for Steinway pianos to the red tunics worn by guardsmen.

The firm bought a woollen manufacturer from the princess's family in the 1950s.

The royal visitor spoke to staff about the fabric used for her husband's wedding military uniform - and how she loved the smell of the wool used in the process.

For his 2011 wedding, William wore his Irish Guards military uniform, reflecting his role at the time as Colonel of the Irish Guards.

Amanda McLaren, AW Hainsworth's managing director, said: "Her love for textiles was clearly there.

"She was commenting that she loved the smell of wool, for example.

"She was fascinated by some of the traditional processes and also things like the dye house where she could see the fabric that is worn by the Buckingham Palace guards…being dyed red, and it really brought home to her the intricacies of the process and the skills of our people."

Wearing an emerald green Burberry suit, Kate chatted to Zeb Akhtar, senior weaver trainer, who talked her through the process of weaving the fabric for the military tunics.

She was shown a full guardsman outfit of bearskin, scarlet tunic and trousers, and ran her hands over the merino wool fabric of the jacket.

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Rachel Hainsworth, who sits on AW Hainsworth's family council, chatted to the princess about Lupton & Co, the woollen business they bought from Kate's paternal family.

She said about Kate: "She knows about the history, her parents have been talking to her about it."

Later, the Princess of Wales continued the textiles theme to her day, crossing the Pennines to visit Standfast & Barracks, a printworks dating back to 1924, in Lancaster.