Carole and Michael Middleton spent the Bank Holiday as guests of Prince Charles at his Scottish retreat.
The couple joined daughter Kate and new husband Prince William at Birkhall, in Aberdeenshire.
The delightful house, which Charles inherited from the Queen Mother, is surrounded by beautiful countryside on the edge of the Queen's Balmoral Estate.
Sources have told The Sun that he and Camilla would only share it with their closest friends.
"The Prince of Wales has made a huge effort with Kate's parents.
"Birkhall is his favourite retreat and the fact they have been invited shows there is a genuine friendship."
William is said to be delighted that his new in-laws seem so at ease in the company of his father and The Duchess of Corwall.
Last autumn the Middletons spent a weekend stag hunting on the estate.