LONDON (AP) — Queen Elizabeth II reveals the secrets of giving a speech while wearing a weighty crown, in unusually candid comments that are part of a new documentary on her coronation and the symbolism of the crown jewels.

Among the revelations of the program airing on the BBC on Sunday is that the crown jewels were kept safe during World War II by being hidden in a biscuit tin buried at Windsor Castle. Though it was known the jewels had been taken to the castle for safekeeping, details had not been widely discussed.

The queen also discusses the challenges in being head of state, and jokes that she can't look down while wearing the Imperial State Crown — which weighs 2 pounds 13oz (1.28 kilos) — because her neck would "break."