WATCH NOW: Princess Eugenie's son August turns two. Article continues after video.
Celebrating the arrival of her grandson into the world, Sarah, Duchess of York shared the sweet snap of Ernest with her followers and an equally wholesome caption.
"Amazing...the importance of being Ernest....thankyou so much, clever Eugenie, Jack, and August Brooksbank," Sarah captioned the post, making a clever reference to the iconic play The Importance of Being Earnest by Oscar Wilde.
In an episode of her podcast, the grandma added that Ernest was "a very seriously beautiful little boy" and that she cried when she found out his name - "It's a fabulous name" she added.
Ernest was reportedly born at the famous Portland Hospital, where stays can cost anywhere between £7,145 and £500,000 depending on the luxury inclusions the new parents choose to opt-in for.
Eugenie and Jack's first child August was born there, as was Meghan Markle and Prince Harry's darling son Archie.
The royal family first revealed their family of three would be growing to a family of four in January, Eugenie sharing a photo of her first son August kissing her stomach.
"We're so excited to share that there will be a new addition to our family this summer," she wrote at the time.
Buckingham Palace also released a statement at the time of the announcement, which read, "Princess Eugenie and Mr Jack Brooksbank are pleased to announce they are expecting their first child this summer."
"The family are delighted and August is very much looking forward to being a big brother."
Eugenie says it was "love at first sight" between her and Jack.
The devoted couple first met in 2010 when Jack was working as a bartender at a ski resort in Verbier, Switzerland and the rest (as they say) was history!
The day before they wed in an interview with This Morning they gushed about each other and revealed their connection was instant.
"It was love at first sight," Princess Eugenie shared.
The 31-year-old was so sure of Jack that she called her mum Sarah Ferguson to tell her the news.
"I think I rang my Mum that night and was like 'I've just met this guy Jack' and that was it I think, and this is how it started," she said.
Eugenie and Jack welcomed their first child into the world in February 2021.
The couple wed eight years later at Windsor Castle, and welcomed their first child, a baby boy named August, on the 9th of February 2021.
"We wanted to introduce you to August Philip Hawke Brooksbank. 💙💙💙"
"Thank you for so many wonderful messages. Our hearts are full of love for this little human, words can't express. We are excited to be able to share these photos with you," Eugenie captioned her official announcement post on February 20th, 2021.