The prince asked the family whether they were proud of him, and chuckled when they responded: “You haven’t seen it (the portrait) yet.”
Charles said he had had a “tiny glimpse” of an unfinished version, before joking: “There is always that slight worry when you pull the curtain down,” to laughter from Mr Reid and his family.
After revealing the new painting, which depicts him sitting in a relaxed pose in a garden scene, the prince flashed a warm smile at Mr Reid before stepping back for a better look.
He nodded with approval as Camilla stepped closer also nodding, and said “well done”.
The new portrait was commissioned by Historic Royal Palaces for Hillsborough Castle ahead of the official public reopening on April 18.