A week after King Charles revealed he's a Swiftie, Prince George snuck a secret Taylor Swift reference into Prince William's Father's Day photo shoot. Following a busy Saturday at Trooping the Colour—at which Prince Louis and Prince George had a ball—the Prince and Princess of Wales's three children sent their dad a special message on Instagram.

Royal fans have been left totally divided over one small detail in a rare ‘casual’ photo of Prince William and Kate Middleton with their three children.

The seriously sweet Instagram post also featured a hidden Taylor Swift reference —pretty unsurprising given that William took Charlotte and George to see the Eras Tour in London. Sadly, Prince Louis didn't attend the epic concert, where the royals met Swift and her boyfriend, Travis Kelce.