The Royal Family are out in force in Windsor, attending the Coronation Concert at the Castle, with the King and Queen in the audience.
The monarch is joined by his son and daughter-in-law, Prince William and Kate Middleton the Princess of Wales as well as two of their children Prince George and Princess Charlotte.
The Prince of Wales stunned royal fans as he appeared on stage to deliver a speech dedicated to King Charles and the key workers of Britain.
While on stage, his wife and kids could be seen watching on and people couldn't help noticing how 'proud' Kate looked of him - and they loved her reaction to his cheeky joke.
At the start of his speech, William told the crowd: "Good evening Your Majesties. Good evening Windsor!
"A huge thank you to everyone for making this such a special evening.
"I want to say a few words about my father, and why I believe this weekend is so important. But don’t worry, unlike Lionel, I won’t go on all night long."
At this joke, Kate could be seen tilting her head to one side and smiling wide, before letting out a little chuckle.
Fans on Twitter rushed to share their thoughts on the sweet moment, with one person saying: "She's sooo proud of him. Her smile is everything."
"She looks so in love," wrote a second.
Another posted: "She's so in love and proud!! That face, her eyes were shining while looking at him."
A fourth proclaimed it to be "so cute".
Others thought she might have made her own joke back at her husband, as it looked as if she said "oh really" in return to him not going on all night long.
Someone else tweeted: "Oh god here I go again bawling at Prince William talking about his nan and dad. Kate looks a proud wife and the King is beaming."
While a different user noticed George and Charlotte also reacting to their dad, adding: "Princess Kate beaming and Charlotte getting George's attention for their father in excitement... SOO SWEET."
