Princess Diana's wedding dress goes on display at Kensington Palace for first time since her death

Princess Diana's wedding dress has gone on display at Kensington Palace for the first time in over two decades.

The iconic gown is the feature piece in the Royal Style in the Making exhibition, which opens today.

The design by David Emanuel is on loan from Prince William and Prince Harry, who have given their blessing for the dress to be displayed 40 years after their parents 1981 wedding.

It has been 25 years since the dress was last shown at the Princess of Wales's former home in 1995, two years before Diana's death in a Paris car crash.

Royal fans in London can see the puffy-sleeved dress encased in glass, complete with its dramatic 7.6-metre sequin-encrusted train, still the longest in royal bridal history.

The dress "features a fitted bodice overlaid at the centre both front and back with panels of antique Carrickmacross lace that had originally belonged to Queen Mary, the groom's great-grandmother", the Historic Royal Palaces website says in it's description.

"Its gently scooped neckline and large puffed sleeves are trimmed with bows and deep ruffles of taffeta, a style popularised by the Princess in the early 1980s, while the full skirt is supported on a mountain of stiff net petticoats to create its famous silhouette."

Also on display is the coral-coloured outfit Diana wore as she and Prince Charles left their wedding celebrations. The Princess of Wales wore the ensemble again during the couple's royal tour of Australia in 1982.

It's the first time the two wedding day outfits have been displayed side-by-side.

Also forming part of the exhibition is a rare surviving toile for the 1937 coronation gown of Queen Elizabeth The Queen Mother.

The toile is a full-size working pattern of the completed gown worn by The Queen Mother to her husband King George VI's big day.

A number of sketches and designs will also be on display, as the temporary exhibition shows "the intimate relationship between fashion designer and royal client" and the "process behind the creation of a number of the most important couture commissions in royal history".

Royal Style in the Making will remain open until January 2, 2022.