For Lady Melissa Percy, growing up at the magnificentAlnwick Castle— the backdrop of the first twoHarry Pottermovies — was a magical experience full of adventure and the perfect inspiration for her outdoor fashion line.

“It’s only now that I have started to appreciate what an incredibly special place it is,” says Percy, 31, tells PEOPLE, adding: “It was a lot of exploring — secret doors and secret rooms, it was a huge adventure playground.”

The 150-room medieval castle has been in the Percy family for 700 years and is the second-largest inhabited castle in Britain, just behind Windsor Castle, home toQueen Elizabeth. As well as standing in as Hogwarts for the first few Harry Potter films, the castle’s state dining room was also used to film a scene in the Christmas special of Downton Abbey. Percy was at boarding school when Harry Potter began filming in 2000. “I didn’t read the books but I watched all the films and I loved them.”

It was upon the sudden death of Percy’s uncle Harry at the age of 42, that her father, the 12th Duke of Northumberland inherited the property and all the titles that came with it (as well as a library containing a mere 15,000 books and a priceless collection of art).

“I’ve grown up with it and got used to it,” she says of acquiring a aristocratic title at age 8, along with her sister, Lady Catherine, now 37, and her two brothers, George, Earl Percy, 35, and Lord Max, 28.

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“We always used to go out [shooting] with Mum and Dad, from the age of four of five and sit with them and watch, look after the dogs or sit in the car and eat sweets, they always made it fun!”

Catching her first salmon at age seven, Percy admits to being a bit of a tomboy and still goes shooting with her friends which includePrince Harry’s ex-girlfriend Chelsy Davy. “She is my best friend in the world, she is heaven.”

It was after the end of her high-profile marriage to Thomas van Straubenzee — a close friend ofPrince William’s (and godfather toPrincess Charlotte) in 2016, that Percy, a former youth tennis pro, went on a soul-searching trip to Japan and came up with the concept ofMistamina, a clothing range for women who share her love of the outdoor life. The line, a fun range of casual crew sweaters with elbow and shoulder patches, each color named after a past or present family dog, is due to launch in the U.S this spring.

“Trying to stay positive and making a conscious effort to think happy thoughts,” she says of all the recent changes in her life, “that’s when you get good things done.”

While Percy and her ex-husband “Van” are “on really good terms now,” the designer says the divorce was a painful period in her life. “I knew it was going to be tough,” she says admitting that she lost most of her friends as a result. “We had been together for seven years and married for two, we just grew apart.”

source: people.com