Princess Diana
Princess Diana's Catherine Walker & Co. dress was once featured at an exhibit in Washington D.C. Pictured: Princess Diana dress at left was made by London designer Catherine Walker for Diana's 1992 tour of India on June 11, 1998. TIM SLOAN/AFP/Getty Images

Princess Diana’s favorite designer will launch its spring-summer 2018 collection that is a range of wedding guest outfits.

Catherine Walker & Co., the popular design brand, has also been worn by Kate and Carole Middleton. Said Cyrus, the brand’s head of design and Walker’s widower, gave People a sneak peek into his collection.

Cyrus said that their range is perfect for those who wish to attend royal weddings or any other type of formal gatherings. However, he refused to comment about Prince Harry and Meghan Markle’s May 19 nuptials. He also did not reveal if the Catherine Walker brand will be worn by some of the couple’s guests.

“We have a very strong 1950s influence which I feel is very feminine, very appropriate for occasion-wear. We have a number of pieces in our new collection that are suitable for mothers of the bride and for the occasion wear in the summer season,” he told People.

“One of the most important features of the spring-summer collection is the part it plays in events such as Royal Ascot horse racing. Worn with the right hat they would be perfect for that event. It is perfect for transitioning from day to evening, whether it is cocktail or a summer wedding,” he added.

When asked what he prefers female guests to wear at weddings, Cyrus said that he likes seeing women in a coat dress. This is attire that Middleton worn has worn at least once.

“These are ideal for weddings where you need to look the part during the day but also transition into the evening. I like to use one-piece coat dresses rather than suits, which are jackets and skirts or dresses, as I think they are very elongating and by virtue of that elongation are quite flattering. Although there is a silhouette that looks like it’s a jacket and dress, it’s not. It’s all one piece,” he explained.

Catherine Walker & Co. was founded in 1977 by Walker herself. She passed away in 2010. Years after the brand was launched, Walker became good friends with Princess Diana. Even after Princess Diana divorced Prince Charles, Walker continued to dress her.