The Princess of Wales was left grimacing after Meghan Markle borrowed her lipgloss in an "awkward moment", according to Prince Harry.
The moment is revealed in Harry's controversial memoir Spare, which contains a string of bombshell revelations and private details about his life and family.
It has long been reported that Meghan and Kate did not share a close relationship in the early days of her royal life - despite the Sussexes along with Prince William and Kate being dubbed the 'Fab Four'.
And in Spare, Harry reveals an "awkward moment" between the two women at the first, and only, official joint engagement between the 'Fab Four' in February 2018.
The outing saw the royals take part in a Royal Foundation Forum, where they were quizzed about their charity work.
And backstage, Harry says: "Meg asked to borrow Kate's lipgloss. An American thing. Meg forgot hers, worried she needed some, and turned to Kate for help.
Kate, taken aback, went into her handbag and reluctantly pulled out a small tube. Meg squeezed some onto her finger and applied it to her lips. Kate grimaced. Small clash of styles maybe."
The detail about the moment comes as Harry's book also sheds new light on what really happened between Kate and Meghan during the latter's time as a working royal.
He also alleges that Meghan upset Kate by saying she must have "baby brain” in the run-up to the Duke and Duchess of Sussex’s 2018 wedding when she was pregnant with Prince Louis.
Meanwhile, he also reveals a private conversation said to have taken place between the two women about bridesmaids' dresses that left Meghan in tears.
It came after a dress for Princess Charlotte was said to be too big - but Harry says that Kate did apologise.
In his ITV interview with Tom Bradby on Sunday night, Harry admitted Kate and William didn't get on with Meghan "from the get-go".
Asked why the relationship got off on a bad note, Harry said there were "lots of different reasons".
He went on: "I don’t think they were ever expecting me to get into a relationship with someone like Meghan, who had, you know, a very successful career.
"There was a lot of stereotyping that was happening, that I was guilty of as well, at the beginning."
Pushed on what he meant by that, Harry continues: "American actress, and that was playing out in the British press in the media at the time as well.
"I had that in the back of my mind, and some of the things that my brother and sister-in-law – some of the way that they were acting or behaving definitely felt to me as though unfortunately that stereotyping was causing a bit of a barrier to them really sort of, you know, introducing or welcoming her in."
Asked specifically what he meant, Harry added: "Well, American actress, divorced, biracial - there's all different parts to that and what that can mean but if you are, like a lot of my family do, if you are reading the press, the British tabloids, [yeah] at the same time as living the life, then there is a tendency where you could actually end up living in the tabloid bubble rather than the actual reality."
Spare by Prince Harry and published by Penguin Random House is out now.
