Kate Middleton sweetly admonishes Prince William for PDA on television

Kate Middleton and Prince William appeared on a special Christmas TV programme "A Berry Royal Christmas" and gave their fans several heart-warming moments to talk about. At one point, the Duchess of Cambridge seemingly sweetly admonished her husband as he appears to gently keep his hand on her shoulder in a moment of rare public display of affection.

BBC One's "A Berry Royal Christmas" aired on Monday night. The Cambridges joined legendary chef Mary Berry in preparing a festive treat for those who are volunteering and working on holidays. The royals even introduced the British food writer to the causes and the charitable organisations they are working with.

There were several moments that showed the world a different side of the royals as they had some intimate conversations with the baking legend. However, there is one moment during the one-hour special programme that caught followers' attention, according to Daily Mail. The brief clip shows Kate Middleton's swift reaction to William's public display of affection. In the clip, the 37-year-old prince can be seen placing his hand gently on her shoulder to which she responds awkwardly by moving his hand away.

Viewers were quick to take to Twitter and express their surprise, as per the report.

The moment took place towards the end of the show when the royal parents sat down with a group of volunteers to chat with them.

This should not come as a surprise to the viewers as royals are rarely seen in such situations. However, FOX News reveals that Myka Meier, a British-American etiquette expert trained by a former member of Queen Elizabeth II's household once told Elle Magazine that there is no such protocol that prohibits the royals from touching, kissing or hugging in public.

"There's no protocol that tells them they can't hug or kiss or touch," she said. "There's no rule book like that. Each senior member of the royal family is trusted to make the judgment calls of what's appropriate and when. It's all about being trusted to make those calls on their own," Meier added.

And when it comes to the Duke and the Duchess of Cambridge, they are usually more affectionate during informal events.

Meanwhile, during the programme, Kate spilled some details about their days in university when she had just started dating Prince William. As per the duchess, during their days at St. Andrews, William would try his hands on a few dishes to impress her.

The couple started dating in 2003 and tied the knot in 2011. Now, they have three children, Prince George, Princess Charlotte, and Prince Louis.