The mystery of whether a painting of a beautiful youth is really of Lawrence of Arabia, an exquisite peacock dress worn by the wife of the Viceroy of India flutters back to life and the dolls' house that inspired Beatrix Potter to write one of her most beloved stories all feature in the brand-new series of Hidden Treasures of the National Trust, narrated by actor and national treasure himself, Toby Jones.

This year, the series showcases experts and volunteers who care for the 500 places the National Trust looks after – such as June, who gets down on her hands and knees in the marble hall at Kedleston Hall to count the cracks in its design masterpiece; Pete, head gardener at Hill Top, Beatrix Potter's Lake District farmhouse, who admits he is frequently mistaken for Peter Rabbit's Mr McGregor; and archaeologist Martin who's trying to unearth one last mystery from under the ruins of Corfe Castle before he retires.