A member of the Royal Collection Trust poses for photographers next to Britain's Queen Elizabeth's 'Mantle of The Order of The British Empire' robe, ahead of the opening of an exhibition entitled 'Fashioning a Reign: 90 Years of Style from the Queen's Wardrobe', at Buckingham Palace, in London, Britain July 21, 2016. [Photo/Agencies]

A member of the Royal Collection Trust, poses for photographers next to Britain's Queen Elizabeth's 'Mantle of The Order of The British Empire' robe, ahead of the opening of an exhibition entitled 'Fashioning a Reign: 90 Years of Style from the Queen's Wardrobe', at Buckingham Palace, in London, Britain July 21, 2016. [Photo/Agencies]

Curator Caroline de Guitar, poses for photographers next to Britain's Queen Elizabeth's green ensemble worn for Trooping the Colour in 2016 marking her official 90th birthday, ahead of the opening of an exhibition entitled 'Fashioning a Reign: 90 Years of Style from the Queen's Wardrobe', at Buckingham Palace, in London, Britain July 21, 2016. [Photo/Agencies]

Curator Caroline de Guitar poses for photographers next to the wedding dress worn by Britain's Queen Elizabeth in 1947, ahead of the opening of an exhibition entitled 'Fashioning a Reign: 90 Years of Style from the Queen's Wardrobe', at Buckingham Palace, in London, Britain July 21, 2016. [Photo/Agencies]

A member of the Royal Collection Trust, poses for photographers next to Britain's Queen Elizabeth's evening gowns, ahead of the opening of an exhibition entitled 'Fashioning a Reign: 90 Years of Style from the Queen's Wardrobe', at Buckingham Palace, in London, Britain July 21, 2016. [Photo/Agencies]