It will be four years this September since Queen Elizabeth II passed away and her son Charles ascended to the throne. Throughout his life, Charles developed a warm bond with the late monarch, who despite being 'Your Majesty' or 'Ma'am' to the family in public, was simply just 'mum' to her children behind closed doors.
Charles gave royal fans a rare insight into their close bond in 2018 with one single word. An unearthed video captured the moment Charles delivered a heartfelt speech at the Queen's star-studded birthday concert at Royal Albert Hall on 21 April - and called her by a more personal moniker.
Charles, who was the Prince of Wales at the time, stood on stage beside his mother, who had just turned 92, and began his speech by addressing her formally as "Your Majesty" before calling her "Mummy". The informal nickname earned a chuckle from the audience and what some thought might have been a humorous eye roll from the Queen before she laughed along.
"I have a feeling that in 1948, when you were 22, you didn't somehow expect that at your 92nd birthday to find your son in his 70th year," Charles cracked a joke in his speech.
Royal fans react to 'adorable' unearthed moment
Nearly eight years on, the moment has resurfaced on social media, with fans praising the Queen's reaction in particular.
"I thought that was adorable…the expression on her face was priceless," one person commented, while others remarked on the late monarch appearing to roll her eyes in response to being called "Mummy".
"The eyeroll. Hysterical. Bless," someone said, while others pointed out she "ran with the joke" and the moment had "great sense of humour".
How the Royal Family referred to the Queen
Behind closed doors, the Queen had several affectionate nicknames amongst her close family. Growing up, Elizabeth was called 'Lilibet' by her parents and grandparents, which her grandson, Prince Harry, went on to name his daughter upon her birth in 2021.
Princes William and Harry would sweetly refer to their grandmother as 'Granny', while her great-grandchildren had a different nickname.
"George is only two-and-a-half and he calls her ‘Gan-Gan'," the Princess of Wales revealed of her son's name for the Queen in an interview from 2016. "She always leaves a little gift or something in their room when we go and stay and that just shows her love for her family."