Meghan Markle and Prince Harry were seen holding hands as they left Westminster Hall following a service honouring the life of Queen Elizabeth II.
The public display of affection as the pair left the service on Wednesday divided opinion.
While the Sussexes held each other’s hand, other royal couples left Westminster Hall with their hands by their sides.
Speaking about the act, royal expert Shannon Felton Spence said: "While there are no formal 'rules' against PDA, we don’t often see it from the royals because usually when we see them they are on the job.
Meghan Markle and Prince Harry PHIL NOBLE
The pair left Wednesday's service hand-in-hand POOL
"They are presenting their most professional appearance. When we see William and Catherine out, they are husband and wife colleagues.
"It does happen, but usually always setting appropriate or a less formal event (like if they are playing a sport).
"That’s why it’s so striking that Harry and Meghan have always been so overtly affectionate with each other.
"It’s not that it’s unusual for a husband and wife, it’s that we’re just not used to seeing it from the royals while they are on the job," she told Fox News.
Ms Spence continued: "I’ll give them a pass for today when they were walking out of Westminster Hall because that procession had to be very traumatising for Harry, and they are all grieving."
Some people took to social media to support the Sussexes over the act.
One person wrote: "Meghan Markle is such a supportive wife to Prince Harry. The best of the British royal family.
While another added: "Keep holding hands Harry and Meghan. It amuses me to see people bothered by it. Lol.”
While others accused the pair of “drawing attention to themselves”.
One user said: "What a shame. Meghan and Harry just had to draw attention to themselves by holding hands.”
Zara and Mike Tindall held hands as they arrived at Westminster Hall, but neither hold royal titles.