One royal fan even went so far as to compare Harriet to Princess Kate, Prince William’s wife.
One fan wrote on X: “Wow, she’s lovely, and has that Princess Catherine elegance.”
Another said: “She looks lovely and perfectly dressed for the occasion!”
Someone else commented: “She is always dressed to perfection.”
A fourth fan said: “Just love her outfit. Perfect summer chic!”
Harriet was first spotted out with Peter last May when they attended the Badminton Horse Trials in Gloucestershire together.
Since then they have stepped out together a handful of times, including Royal Ascot just last month.
It is believed Harriet gets on well with Peter’s royal relatives, including his mum Princess Anne, 74, and his sister Zara Tindall.