The dress, designed by David Emmanuel, will be on display from Thursday as part of a new fashion exhibition called “Royal style in the making”. It is on loan from Prince William and Prince Harry.
They have been assembled from the archives of the royal family’s couturiers, including David Emanuel, David Sassoon and Norman Hartnell.
Matthew Storey, exhibition curator at Historic Royal Palaces, told the MailOnline that said his favourite drawing in the exhibition is of a blue floral dress designed by David Sassoon in 1988.
"The dress became known as her "caring dress" because she often wore it on visits to hospitals or to meet children, knowing that they loved the bright, colourful pattern,' he explained.
"She decided not to wear the large matching hat that was designed to accompany it, as she said you couldn't cuddle a child in a hat.
"She would also sometimes wear chunky jewellery when she knew that she was going to meet children, as they would enjoy playing with it.
"This really illustrates just how carefully she considered the people she would meet when selecting outfits for her many public engagements."
A rare surviving toile for the 1937 coronation gown of Queen Elizabeth the Queen Mother, consort of King George VI, is among the other items of royal fashion history which are going on display.
Original sketches, fabric swatches and unseen photographs from the royal ceremonial dress collection will also be displayed to try to bring to life the skills that couturiers added to the royal wardrobe.
An array of glittering gowns and stylish tailoring which have been created for three generations of royal women is also billed to be among the items on show at the Kensington Palace Orangery.
The exhibition will run at Kensington Palace from June 3 to January 2 of 2021.