Prince Harry and Meghan Markle
Prince Harry and Meghan Markle attended a wedding a month after they exchanged "I do's." Pictured: Prince Harry and Meghan Markle wave as they leave Windsor Castle after their wedding to attend an evening reception at Frogmore House, hosted by the Prince of Wales on May 19, 2018 in Windsor, England. Getty Images/Steve Parsons

Meghan Markle and Prince Harry attended a wedding a month after they exchanged "I do's."

On Sunday, the Duke and Duchess of Sussex were photographed smiling and laughing at Celia McCorquodale and George Woodhouse's nuptials at St. Andrew and St. Mary's Church in Stoke Rockford, Lincolnshire. Celia is the younger daughter of the Princess of Wales' sister Lady Sarah McCorquodale. The bride sported the same tiara that Princess Diana wore when she married Prince Charles, Express reported.

Prince Harry and Markle wore a coordinated blue ensemble. The former "Suits" actress opted for a long-sleeve blue-and-white floral print Oscar de La Renta dress, which is sold for only $5, 490. On the other hand, Prince Harry opted for a three-piece suit with a blue tie to coordinate with Markle's dress, according to People. Markle paired her get up with a simple but elegant fascinator.

According to Prince Harry's ex, Cressida Bonas, for her, the most challenging part of attending weddings is choosing the best dress and hat. Bonas was among the guests whom Prince Harry and Markel invited to witness their exchange of vows at St. George's Chapel at Windsor Castle on May 19.

"Friends are starting to get married, which means the dilemma of British wedding attire. Hats," Bonas wrote. "Why do I find hats so tricky? Tricky to wear, tricky to look at, and extremely tricky for the poor soul sitting in the pew behind. Most of the time I avoid headgear. This can prompt disapproving looks from the older generations."

"Last weekend I attended the royal wedding. The invitation clearly stated that guests must wear hats. Yikes. I opted for a minimal feathered number — and can only hope I got it right," she continued.

Celia's wedding was Markle's first outing after her first solo trip with Queen Elizabeth II. On Thursday, the royals visited Chester to officially unveil a new bridge in Widnes, Cheshire and open the Storyhouse Theatre. It's also the first wedding they attended as a married couple.

Also, Prince Harry and Markle have just returned from their honeymoon. However, the pair is not expected to have a child anytime soon as they have a hectic schedule.

"I think what other royals have decided to do is a guide here. Their schedules will be so busy so I think they'll wait," Richard Fitzwilliams said.