Sarah Ferguson has been watching her younger daughter’s growing baby bump with undisguised delight. “I am very excited,” Sarah tells Closer exclusively in the latest issue, on newsstands now. “The news has brought the most wonderful sense of joy to me.”

The baby of Princess Eugenie, 30, and Jack Brooksbank, 35, will give the whole royal family a reason to celebrate when he or she arrives in February. The child will be Queen Elizabeth II’s ninth great-grandchild and make Sarah a first-time grandmother. “The great thing about grandmothers is you get to spoil [the kids] rotten and enjoy all the fun and mischief of childhood, but ultimately it’s not you who’s in charge,” says Sarah, 61, with glee.

She is already thinking of ways to indulge the baby! “I’m going to have a lot of fun just as I did with my children. I bought mine every kind of Barbie doll there was just so we could build the sets together,” Sarah explains. “It brings me great happiness to play with children.”

Britain Princess Eugenie Engaged, London, United Kingdom - 22 Jan 2018
Jonathan Brady/AP/Shutterstock
Mandatory Credit: Photo by Jonathan Brady/AP/Shutterstock (9330860a)
Britain’s Princess Eugenie and Jack Brooksbank pose for the media in the Picture Gallery at Buckingham Palace after they announced their engagement in London, . Princess Eugenie is engaged to be married later this year, several months after her cousin Prince Harry’s nuptials. Eugenie, the daughter of Prince Andrew and his ex-wife Sarah Ferguson, will marry Jack Brooksbank in the fall, Buckingham Palace said Monday
Britain Princess Eugenie Engaged, London, United Kingdom – 22 Jan 2018

The baby has inspired Sarah, who recently authored her first historical romance novel, Her Heart for a Compass, to write a new children’s book. “The Adventures of Charlie, Blue and Larry the Lamp Post will be coming out in February or March. This book will be dedicated to my first grandchild,” confides Sarah, who plans to follow it up with 12 more volumes over the next year.

As they await the baby’s arrival, Eugenie and Jack have moved back to the Royal Lodge, near Windsor Castle, to be near Sarah. “I have always been close with my girls,” says Sarah. “It’s such a joy to see them embarking on this next phase of their lives.”

For this story and more, pick up the latest issue of Closer magazine, on newsstands now!