Some fans pointed out that Zara and Mike Tindall seemed to be at Kensington Palace for the evening garden party.
Zara looked beautiful in a black midi dress from Rebecca Vallance, the After Hours One-Shoulder Midi Dress in black.
The midi gown currently retails for £658 on Farfetch but it can also be purchased from Mytheresa for £473.
The fashion website described the dress as the perfect option for an “elegant party”. It said: “Get party-ready in the elegant After Hours dress from Rebecca Vallance.
“Made from the label’s signature bonded crêpe, the midi-length style features an asymmetric ruffled neckline that rests stylishly on one shoulder.”
Princess Anne’s daughter paired the black dress with her Aquazzura black heels, the Forever Marilyn 85’ Black Suede Pumps.
Zara also donned a silver clutch bag, the Ellipse Clutch in Champagne Coarse Glitter from designer Jimmy Choo.
For jewellery, she chose a pair of maxi pearl earrings and wore a discreet silver watch.
On social media, fans loved Zara’s chic look with many saying she looked “gorgeous” and very glamorous.
Instagram user @cadmanjones commented: “She looks amazing in this,” and another opined that the royal looked “stunning”.
@florence.pit added: “I love this look, so stylish, everything works well together. Most of all I like the way she looks at her husband.”