Zenouska is Marina Ogilvy and Paul Mowatt's daughter and she is currently 61st in line to the throne.
Zenouska shared several pictures from her birthday celebrations
The 31-year-old, who is Head of Marketing for jewellery brand Halcyon Days, posted several pictures from her birthday celebrations at home and it looked a lot of fun.
In one picture, the royal can be seen posing with a dog underneath a bunch of balloons that spell out "Zen", in reference to her name. Several other snaps see her happily pose with her best friends, who prepared a special dinner to mark the occasion.
Zenouska with her grandmother Princess Alexandra
The last picture of the carousel shows off her stunning birthday cake, with features four candles and a "Zennie Babes!" dedication.
While Zenouska is rarely seen with her royal family, she has in the past appeared on the Palace balcony at Trooping the Colour, most recently in 2018 and 2019.
Zenouska and Princess Eugenie used to attend the same school
Her public Instagram is a delight for royal fans as before the pandemic she used to share pictures from her trips to the Ascot racecourse and even several from Princess Eugenie's and Lady Gabriella Windsor's royal weddings in 2018 and 2019.
Zenouska's mother is Prince Charles' goddaughter and now lives in a cottage on the grounds of Windsor Castle.
A pregnant Marina and Paul married in 1990, with the Queen's consent, and divorced seven years later, after welcoming two children, Zenouska and Christian.
At the time, Marina shocked with her choice of wedding dress, opting for a black velvet number with a matching black hat.