Kate Middleton and Prince William Showed Some Rare PDA at Their Latest Royal Event

Kate Middleton and Prince William had their first joint engagement post-maternity leave this morning. The couple attended the inaugural Global Ministerial Mental Health Summit at London County Hall, where they met with leaders of various mental health initiatives and learned about their work. The Duke and Duchess of Cambridge are familiar with the field, as they and Prince Harry helm the organization Heads Together, which aims to end the stigma of mental health.

Middleton arrived in a lilac, A-line Emilia Wickstead dress and a crocodile Aspinal of London handbag with nude pumps. Meanwhile, her hubby looked sharp in a black suit and dotted red tie.

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The couple often refrains from showing affection in public, especially at work events, but Prince William sneakily put his hand on Kate's back as they made their entrance.

Prince Harry and Meghan Markle, on the other hand, show PDA more openly, even if they're attending an official engagement. Last week, they hugged it out at the Coach Core Awards and held hands, as they often do, throughout their first visit to Sussex.

There's no formal "protocol" barring royal couples from showing affection in public; instead, "it’s all simply a matter of preference for each couple and is also likely dependent on the nature of the event they are attending," etiquette expert Myka Meier previously told People.

William and Kate, for example, are more likely to refrain from showing PDA because they're "working representatives of British Monarchy" and want to "remain professional," Meier told People.

However, the adorable moments at today's engagement didn't stop with the brief PDA.

They shared a laugh while painting a canvas with artist Dairo Vargas:

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And they chuckled again while sitting on a "friendship bench":

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This isn't the only time we'll see the Cambridges this week. On Friday, they're slated to attend Princess Eugenie's wedding at Windsor Castle. (The bride is William's cousin.)

Princess Charlotte will be a flower girl at the ceremony, while Prince George will be a page boy. Considering the siblings' reputation for stealing the show at family weddings, Friday's nuptials will be one family outing we won't want to miss.

This article originally appeared on Harper's BAZAAR US.