The 'secret' making of Meghan Markle's royal wedding gown

The custom gown was designed by Givenchy's first female artistic director.

Markle, now the Duchess of Sussex, already knew what she wanted in her wedding dress: something timeless, elegant and appropriate, Scobie added.

“I think she had seen my work and knew what I did,” Waight Keller said in comments to the press after the wedding. “I think she loved the fact that I was a British designer and working in a house such as Givenchy, which has its roots in a classical, beautiful style from the time of Hubert [de Givenchy] himself.”

After Markle officially chose Waight Keller to create her dress, the designer had to keep it a secret from everyone, even her own family, until the wedding day.

Mostly through discreet texts and phone calls, Markle and Waight Keller went back and forth on designing the dress before two teams signed nondisclosure agreements and got to work on it at Givenchy's Paris headquarters and an undisclosed London warehouse, according to Scobie.

Creating the iconic dress "was all about keeping the secret," Waight Keller said.

Hundreds of hours of meticulous stitching later, the finished gown was transported to Windsor Castle for a final fitting in May and was revealed to the world last Saturday.

Keller called the royal wedding a "dream day" in a post on Instagram.

Waight Keller also told the press that Prince Harry thanked her for designing the dress for his bride.

"He came straight up to me and he said, 'Oh my God, thank you! She looks absolutely stunning,'" Waight Keller recalled. "Well, I think everybody saw on television -- he was absolutely in awe, I think. She looked just incredible and it showed."