Although the royal mom of two was formally titled the Duchess of Cambridge on her wedding day – and colloquially-called Princess Kate by fans and PEOPLE alike – it's the "princess" title that is displayed on the inside of her luxe wedding gift gown.
The gorgeously-embroidered name tag, "Princess Catherine," is revealed in the His and Hers bespoke silk-lined cashmere dressing gowns – navy blue for Prince William and white for Kate – that were made for the couple by Nottingham, England, designer Daniel Hanson on their royal wedding day in 2011.
Hanson, and his small band of 12 employees, who also have also made gowns worn by singer Elton John and movie stars Brad Pitt, Halle Berry and Meg Ryan, were asked to create the stunning garments by royal household suppliers Turnbull and Asser as a wedding gift.
"Because they were presents, the decision about what to use inside had to be made before the wedding. Their titles weren't disclosed until the wedding, so we had to speculate on what she would be called," designer and owner Daniel Hanson tells PEOPLE. (The chatter about what Kate should be called has caused some lively debate.)
"We were very proud as a company to be commissioned by Turnbull and Asser to make them," he continues.
The discreet designer wouldn't reveal too much more about the royal order, including the exact cost. But the top of the range (heavily embroidered versions) can cost as much as $11,100, but William and Kate's robes are not thought to cost as much since they have relatively little embroidery.
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That said, any garment with "Prince William" and "Princess Catherine" stitched inside is likely to have a high value.
What is certain is that the silk-lined cashmere gowns are warm and cozy. "It is a totally seasonless product," Hanson tells PEOPLE. "If you wear cashmere against your skin, you will cook, but if you wear cashmere with a silk lining, it will keep you cool in summer and warm in winter."
"The joy of this is that silk against your skin won't heat you up beyond room temperature. Whereas, if you brought an egg to the boil, for example, and wrapped it in cashmere, such is the insulation properties, you could hard boil it."
Each dressing gown likely starts around $3,200, rising to around $4,160 for a bespoke creation. "A dressing gown worth [$3,000 to $4,000] is for a specific kind of shopper," Hanson says. "It is for someone who has got everything and wants a little bit more."
The highest priced products – at more than $11,000 – are those that are heavily embroidered, and are sent to India fir for about 250 hours of detailed decorative stitching.
"There is exquisite embroidery in India. There is still a culture there where people work with their hands," adds Hanson.
The company, which has been called upon to make 250 costumes for the Keanu Reeves sci-fi and Samurai film 47 Ronin 47, has also made several items for Elton John, who posed in the company's gowns with his children, Zachary, 5, and Elijah, 3.
The singer, 68, orders his via Neiman Marcus. "We deal directly with personal shoppers for him. He has been dealing with us for 20 years," says Hanson, whose products are also available in the U.S. at Brooks Brothers and Bergdorf Goodman.
"We don't view people like Elton John as a client, but as a benefactor because he and people like him are putting money back in the chain to traditional manufacturers like us."