Penny Junor, royal expert, said on the Channel 5 documentary Secrets of Royal Palaces how William and Kate’s relationship “blossomed” at the cottage.
She said “there is an enormous freedom” at Tam-Na-Ghar that the couple enjoyed.
Glynis Barber, narrator of the documentary, added: “It’s the one palace they can almost guarantee privacy which is probably why so many royal relationships have blossomed there.
“The Duke and Duchess of Cambridge spent time there when Kate was first being introduced to the family.”