The Prince of Wales was supported by the Duchess of Edinburgh in a very rare joint appearance on Tuesday evening, for the premiere of the documentary, Rhino Man hosted by the Prince's taskforce, United for Wildlife.
A video clip has since emerged inside Battersea Power Station, where Prince William introduces Duchess Sophie by saying: "This is my aunt."
A royal onlooker shared the moment on Twitter, writing: "This is sweet. Prince William introduced The Duchess of Edinburgh as his aunt, at yesterday’s event. William: 'this is my aunt'."
Sophie can then be seen shaking the hand of the person that William introduced her to.
Fans branded the candid content as "wholesome" with one commenting: "She's not a duchess to him, she’s his aunt, she's his family. I love it." Another added: "He adores Sophie, I’m so happy to see them doing something together. Sophie is so down to earth, and is a really lovely lady," and a third wrote: "Something wholesome about this engagement and I can’t correctly explain what!!"
The film, Rhino Man, marks the tragic murder of Anton Mzimba at the hands of wildlife traffickers and follows the training of the next generation of South African wildlife rangers and the role they play in protecting rhinos from poachers.
Speaking about the documentary, William said: "The murder of Anton Mzimba is a stark reminder of the daily dangers that all rangers face around the world protecting the natural world from the international criminal organisations that seek to profit illegally from wildlife and I’m proud to see his life and legacy recognised in Rhino Man.
"This is not a burden they can bear alone. An effective response to this vicious crime demands attention and collaboration across the entire chain of criminal activity, not just on the front line.
"That is why United for Wildlife, through its global financial and transport taskforces, and wider alliance of partners, has taken action to ensure that those involved in wildlife crime will be met with an international response as powerful and co-ordinated as any other serious and organised crime."
Another cause close to the Prince's heart is the tragedy that happened at the Grenfell Tower six years ago.
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He and his wife shared a single green love heart on Twitter on Wednesday to their 2.8 million followers, showing solidarity to the survivors, rescuers and paying tribute to the lives lost.
The sombre post was sent at 9pm in the evening, and had no words at all.
Last year, the royal couple attended a memorial service to mark the fifth anniversary of the tragic event, and both of them looked visibly moved.
A total of 72 people were killed during the blaze in June 2017, and William and Kate have been dedicated to supporting the survivors and marking the memory of those who lost their lives since.