A chiffon dress worn by the late Queen Elizabeth and a ball gown worn by her sister Princess Margaret are among the regalia going on display in County Down.

The fitting backdrop of Hillsborough Castle, itself a royal residence, is hosting an exhibition that gives an intimate glimpse into the world of the royal fashion designers.

The castle, which has been at the heart of many political and diplomatic encounters, will be transformed into regal elegance to feature garments created for many high-profile members of the Royal Family.

As well as Queen Elizabeth II and her sister, other outfits are on show including those worn by the Queen Mother and sketches for dresses to be worn by the late Diana, Princess of Wales.

Running from 15 March 2025 – 4 January 2026, the exhibition – Royal Style in the Making – tells the story of the working relationship between fashion designer and royal client.

“Visitors will gain an intimate perspective on the design process, from initial sketches to finished garment, that helped define the visual identity of the Royal Family over the past century,” curator Claudia Acott Williams said.

“Royal and ceremonial dress is very different from fashion, it’s not the same as designing fashionable gowns, royal dress is an incredibly performative mode of dress.

“It’s designed to tell a story, to create moments of pageantry and spectacle.”

Historic Royal Palaces hope the exhibition will give visitors a sneak peak behind the scenes of the work of five of the 20th Century’s most important royal couturiers: Madame Handley-Seymour, Norman Hartnell, Hardy Amies, Oliver Messel and David Sassoon.

On display is a full-sized working pattern for a completed gown which would be worn by Queen Elizabeth (later the Queen Mother) at the coronation of King George VI in 1937 at Westminster Abbey.

Known as toile, it is a preparatory garment, by court dressmaker Madame Handley-Seymour, that is cut to the body in a series of fittings.

Ms Acott Williams explained that “it’s like a 3D sketch”.

“This is a really extraordinary insight into how such a garment is created and the fitting process as this would have been fitted to the Queen’s body,” she said.

Visible on the garment are little tacking threads that Madame Handley-Seymour would have used in the cutting and fitting process, as well as patches of embroidery that have been added during the design process.

Madame Handley-Seymour was the favourite designer of Queen Mary of Teck and was recommended to her daughter-in-law, the future Queen Elizabeth (later the Queen Mother).

“As a young woman marrying into the Royal Family she did the appropriate thing and wore the designer that her mother-in-law advised, and she designed her wedding dress in 1923 and then her coronation dress in 1937,” Ms Acott Williams explained.

Sketches for the Queen Mother by Norman Hartnell are also on display.

Norman Hartnell would go on to design both the wedding and coronation dresses for Queen Elizabeth II.

“I think that personal relationship was absolutely critical, we know that the Queen Mother and Norman Hartnell had a wonderful relationship, they were very close,” Ms Acott Williams added.

Letters from Queen Elizabeth II to Norman Hartnell are displayed as part of the exhibition showing the direct line of communication between the royal women and designers.

Similarly with Princess Diana, sketches by David Sassoon are on display with her handwritten notes, such little ticks and “this in dark blue please”.

“There is a very personal relationship between them, they would have long fittings at Kensington Palace sat on the floor with fabric samples all over the place.”

A salmon-pink silk chiffon dress with bat-wing sleeves, worn by Queen Elizabeth II and created by her royal dressmaker, Hardy Amies, is also on display.

She wore it as part of her state visit to Bahrain in 1979 and also to a film premier in London a few months later.

“Hardy Aimes is quite important in ushering her [Queen Elizabeth II] look forward, a slightly more youthful modernity, particularly around bright colours that she was so often seen wearing in later years,” Ms Acott Williams explained.

“The 70s is a moment of great political and social change and there is a real impetus within the Royal Family to be seen to reflect the times.

“I think she [Queen Elizabeth II] does start to make bolder choices in the 1970s and Hardy Aimes is quite an important person in helping shepherd her through that.”

An 18th Century-style blue and gold ball gown worn by Princess Margaret to a charity event at London’s Mansion House in July 1964 is another highlight of the exhibition.

It was was designed by Oliver Messel who was one of the leading designers for stage and screen, and the uncle of Princess Margaret’s then husband – Antony Armstrong-Jones, 1st Earl of Snowdon.

“Margaret actually sees his [Oliver Messel’s] production of A Midsummer Night’s Dream in 1938 when she’s less than 10-years-old and she’s totally mesmerised by it, and then several years later she marries his nephew and they become incredibly close, and even beyond her divorce they remain great friends,” Ms Acott Williams explained.

“I hope this exhibition shows the thought, research, craftsmanship that goes into these gowns. They are created by the greatest crafts-people that Britain has to offer.

“We are all familiar with these women and with what they wear but what we wanted to understand more about the people who were dressing them and about how those relationships worked,” Ms Acott Williams added.