But there was a slight issue as he instead posted four pictures of his other daughter Princess Eugenie. This included one of Eugenie on her wedding day. The tweet read: “Happy Birthday Princess Beatrice, Thank you to everyone for the lovely birthday wishes!”
It is not clear whom was responsible for the awkward tweet but it was promptly deleted.
Twitter users made it clear they noted the mistake, however: “Emmm this is a wee bit awkward?!?!”
Another joked: “I never know who is Eugenie and who is Beatrice – thank god I’m not alone and their dad have the same problem.”
Sarah Ferguson, now divorced from Andrew is the mother of the two Princesses.
They are ninth and tenth in the line of succession respectively.
Eugenie used her Instagram to write a sweet birthday message to her elder sister: “You have been bossing it since before I was born and continue to be the most wonderful person, friend and big sister… Happy Birthday to you Beabea!! Xx”
Andrew’s Instagram appeared to not make the same mistake as he posted four pictures of the correct daughter.
Meanwhile, Sarah posted: “Happy Birthday dearest Beatrice.”
Both Beatrice and Eugenie were born in London’s Portmore Hospital.
This is the same hospital that saw the birth of Archie Harrison Mountbatten-Windsor, the son of Prince Harry, the Duke of Sussex and Meghan, Duchess of Sussex.
Eugenie’s birthday is 23rd March.
She is 29 years old.