The fashion industry is notoriously catty behind the scenes, but the famous Irish designer Paul Costelloe, long a favorite of the late Princess Diana as her personal designer from 1982-1997, let loose on Di’s daughter-in-law Kate Middleton in a very public way last week.

Costelloe, 71, a native of Dublin whose vast fashion empire is based in London, told the Irish Independent that he was “very disappointed” with Kate’s casual cover shot for U.K. Vogue last year.

“It wasn’t like Princess Diana at all. Kate’s not as individual as Princess Diana. She’s not offering the excitement, unexpectedness and vulnerability that Princess Diana did,” Costelloe sniffed.

Perhaps breeding has something to do with that, he suggested.

'I was very disappointed with Kate Middleton's Vogue cover' - Irish designer Paul Costelloe https://t.co/wz9immJO09 pic.twitter.com/NNk68R246f

— Independent Style (@Indo_Style_) October 25, 2016

“Kate has a very different background to Princess Diana. Diana’s mother was an aristocrat while Kate’s was an air hostess. She’s very obedient.”

Meow!  Still, Costelloe did have some nice things to say about the dutiful duchess.

“She’s filling the perfect daughter-in-law role,” he said.  “She’s her mother’s daughter, and it’s clear her mother plays a very important role in her life, which is good.”

Costelloe has dressed other members of the British royal family, and would love to do the same for Kate.

"It would be amazing if she could wear my collection, although she has worn Orla Kiely and we should be very proud of her," he said of the Irish designer.

Hmmm…given his outspoken remarks, Costelloe probably shouldn’t wait too long for a call from Kate and her air hostess mother.

Read more: Kate Middleton can trace Irish lineage to High King Brian Boru

Kate Middleton.