Mirren, of course, won an Academy Award for 2006 portrayal of the British monarch, prompting Prince William to joke that he should call her "Granny."
Kate reportedly recalled the joke on Monday night, telling Mirren, "my husband called you Granny last night."
Mirren said the queen left her starstruck.
“I am genuinely always astounded by her aura, her twinkle, her presence," Mirren told the Telegraph. "It never fails to surprise me and again it’s what everyone says when they meet her — it was what overwhelmed me the first time I met her."
The royals' other guests included Uma Thurman, Hugh Laurie, Helena Bonham Carter, Joely Richardson, Roger Moore, director Steve McQueen, Ralph Fiennes, Angela Lansbury and Joan Collins.
[The Telegraph, Us Weekly]