One of Princess Margaret's Most Lavish Ball Gowns Is on Display for the First Time in Nearly 50 Years

A hidden gem from the royal costume archives is on display for the first time.

A dramatic ballgown worn by Princess Margaret serves as the grand finale of the new Royal Style in the Making exhibit at Kensington Palace. Queen Elizabeth's younger sister donned the over-the-top piece of wearable art at the Mansion House in London when she attended an 18th century-themed charity ball in aid of the Friends of St. John's.

Designed by Oliver Messel, the sumptuous turquoise silk gown with lace sleeves and cinched waist made its debut in 1964. Princess Margaret had been a longtime fan of the renowned theatrical costume designer before she counted him as a family member — Messel was the princess's uncle-in-law as a result of her 1960 marriage to Antony Armstrong-Jones.

In fact, Messel designed the costumes for a 1938 production of A Midsummer Night's Dream, that the Queen Mother took Princesses Elizabeth and Margaret to see when they were children.

"He had an ability to create an incredible, fairy tale world out of almost nothing," said Royal Style in the Making curator Matthew Storey. "It's said he could create a fairy tale headpiece for a ballerina out of pipe cleaners and cellophane."

Messel later moved to the Caribbean, where he designed the royal's beloved villa on the island of Mustique.

The designer also planned to get rid of his archive of models and designs upon his move. However, Princess Margaret saved the pieces by storing them at Kensington Palace.

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A highlight of the royal fashion exhibit is Princess Diana's wedding dress — in fact, one of the reasons the recently-restored Orangery at Kensington Palace was chosen as the venue for the display was its ability to show off the full length of the bridal gown's 25-foot train.

The Orangery was built in 1704 and 1705 for Queen Anne, and she used the space for parties and entertaining. It now houses a restaurant, a perfect spot for traditional afternoon tea.

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Royal Style in the Making marks the first time Princess Diana's bridal ensemble has been displayed in more than 25 years. It previously was part of a July 1998 exhibit at Diana's ancestral home, Althorp.