Designer David Sassoon is one of the only labels to have designed for every member of the royal family (except the Queen), his most famous client being Princess Diana.
The display will also include a series of sketches of dresses made for Diana, annotated by the royal herself with her musings and ideas.
"We called it the fairy dress, because it was so princess-like," he recalled. "The day after she wore it, I started receiving hundreds of letters from children telling me how much they adored it. It was a child's vision of the perfect princess dress."