Princess Diana was given this codename to keep her wedding dress secret

Princess Diana's 1981 wedding dress, valued at £9,000 (equivalent to £34,750 in 2019), was one of the most talked-about subjects at the royal wedding. It became one of the most famous dresses in the world, and was also considered one of the most closely guarded secrets in fashion history. Buckingham Palace as well as the gown's designers, Elizabeth and David Emanuel, had to go to great lengths to ensure that not even minor details of the gown were leaked before the royal was seen in it.

To ensure the secrecy, Princess Diana was given a secret codename so that fewer people knew who they were working on the gown for, as revealed by royal expert Jonathan Mayo in a report for Mail Online. Designer Elizabeth Emanuel recalled about the dress, "We were so worried, we had shutters on the windows and left false trails in our bins and put in false threads. Diana was given the codename 'Deborah.'"

The amount of secrecy was so high that the designers had also made a spare wedding dress, which would have acted as a stand-in if the design was revealed before Diana's big day. A parasol in a matching taffeta was also created to be used by Diana in case the wedding day turned out to be rainy.

The Princess of Wales had to make repeated visits to the designers' small central London studio for fittings, as she had lost two stone since her engagement, with her waist dropping from 29 to 23 in. When she finally wore the dress featuring large puffed sleeves, a full skirt, and soft touch fabrics on her big day, her grandmother-in-law The Queen Mother went into her bedroom and exclaimed, "My dear, you look enchanting!"

Diana's ivory taffeta dress, decorated with antique lace, hand embroidery, sequins, and 10,000 pearls, had an iconic 25-foot (7.6 m) train as the bride wanted to have the longest train in the royal wedding history. However, the massive train also caused a huge issue as the dress was badly wrinkled when the royal arrived at the Westminster Abbey for her wedding.

This was because the gown's designers were late in realising that they had to keep the train's length according to the size of the glass coach Diana and her father rode in to the ceremony. They found it difficult to fit the dress inside the glass coach, and the train was badly crushed despite Diana's efforts, causing visible wrinkles when she reached the cathedral.