The Duchess of Cambridge’s brother posted the cheeky snap on Instagram.
In the photo, Alizee walks ahead of James through the countryside as she shows off her incredible figure in the skimpy outfit.
Three of the businessman’s dogs can be seen running around.
James wrote in the caption: “When you think it’s nearly autumn but September throws you a heatwave #dogwalking #hunterboots #september #dogwalkingoutfits.”
The post prompted a string of comments.
One of James’s followers wrote: “The boots are superb!”
Another said: “Love the beach look with the hunter boots haha, your fiance is so cool.”
A third commented: “Brilliant Alizee!”