Several of Meghan Markle's former Suits co-stars and some crew are believed to be attending the nuptials on May 19, and reports reveal that some of them have approached the show's wardrobe department to help them source appropriate attire.
The official dress code is "dress uniform, morning coat or lounge suit" with two outfits required. Men are asked to wear a morning suit.
However, guests coming from the States and Canada, which is where many of the actors are based, have been having difficulty with the code, according to The Telegraph.
"Last time I was there, I happened to run into a couple of people in wardrobe who were helping getting things made for some of those that are going," a source told the newspaper.
"They were just helping with some of the ladies outfits, helping with the dresses and the hats.
"I think it's just a couple of of people they are helping with it. I don't think they're making the men's clothing, I think they will be wearing Morning Suits.
"I understand everyone is to wear a hat of some kind, there are a couple of choices... whatever they wear in England, they wear those little side hats."
Meghan's last episode with Suits before she ditches acting to join the Royal Family aired last week with her character Rachel Zane marrying Mike Ross, played by Patrick Adams.
Adams is believed to be attending the wedding along with Rick Hoffman, Gabriel Macht, Sarah Rafferty and Gina Torres.
Earlier this week The Hollywood Reporter quoted a source who is invited to the wedding but struggling with the dress code.
“Two outfits are required for the May festivities, with the men asked to wear a morning suit, which, a few invitees have learned, isn’t particularly easy to secure stateside," they said.