Among the celebs spotted in the crowd were Taylor's boyfriend Travis Kelce, his brother Jason Kelce and wife Kylie, Bridgerton's Nicola Coughlin, Queer Eye's Jonathan Van Ness, Salma Hayek, Leslie Mann and Cara Delevingne.
They also got to meet Taylor, with Tay posting a selfie on social media of her and Travis with the royal trio.
"Happy Bday M8! London shows are off to a splendid start," she captioned the photo, tagging @princeandprincessofwales.