Why Kate Middleton Didn't Attend Taylor Swift's Eras Tour With Prince William

Prince William was seen shaking it off at Taylor Swift's Eras Tour on Friday. Here's why Kate Middleton was noticeably absent.

There were a couple royal blank spaces where Kate Middleton and Prince Louis should have been during night 1 of Taylor Swift's Eras Tour in London.

On Friday, Prince William was joined by his and Kate's two oldest children, Princess Charlotte, 9, and Prince George, 10, for the first show of the GRAMMY-winning singer's London run at Wembley Stadium, and Kate and Louis were noticeably absent. 

Kate Middleton and Prince Louis were noticeably absent from Friday's Eras Tour concert in London. - Getty

ET has learned that Kate, 42, stayed home with Louis, 6, while William, George and Charlotte shook it off during the star-studded concert. According to a source, Kate -- who made her public debut following her cancer diagnosis during last week's Trooping the Colour -- will not attend any future shows. 

"Princess Kate is not expected to attend any future Taylor concerts. Her appearance at the King's Trooping the Colour doesn't mean she is returning to a full schedule of public engagements yet," the source says. 

The Princess of Wales went public with her cancer diagnosis in March.

After Friday's show, both William and Swift celebrated the evening with pics. The heir to the British throne took to his official social media platforms to share a selfie of him and his two oldest children with the "Blank Space" singer, 34.

"Thank you @taylorswift for a great evening! #LondonTSTheErastour," the photo caption read.

The source notes that the photo was taken before the GRAMMY-winning singer took the stage at Friday's concert.

In turn, Swift took to her social media to share another selfie of her, the royals, and boyfriend Travis Kelce, 34.

"Happy Bday M8! London shows are off to a splendid start 🇬🇧🇺🇸🤝 @princeandprincessofwales," she wrote. 

The pic also marked her and Kelce's first Instagram grid moment. 

Inside the show, William couldn't contain his excitement as he was seen bopping around to "Shake It Off." 

William's been a Swiftie for some time. You'll remember he and Swift took the stage alongside Jon Bon Jovi back in November 2013 at the Centrepoint Gala Dinner at Kensington Palace in London, where they belted out "Livin' on a Prayer."

There's no denying that London has brought the star power. Swift's shows have been attended by various celebrities, including Ashton Kutcher, Mila Kunis, Tom Cruise, Jason Kelce, Kylie Kelce and Hugh Grant.

Swift's final run at Wembley for this leg will be on June 23. The "London Boy" songstress will make her return for five more shows at the venue on Aug. 15-17 and Aug. 19-20.

For more celebs at the London Eras Tour, click below.