Harry Potter TV Series Secrecy Reportedly Involves Codenames, Phone Bans and Disappearing Messages — as Prince William and Kate Visit Hogwarts Express

https://www.ign.com/articles/harry-potter-tv-series-secrecy-reportedly-involves-codenames-phone-bans-and-disappearing-messages-as-prince-william-and-kate-visit-hogwarts-express

Tom Phillips Sep 29, 2025 · 2 mins read
Harry Potter TV Series Secrecy Reportedly Involves Codenames, Phone Bans and Disappearing Messages — as Prince William and Kate Visit Hogwarts Express
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Warner Bros. is keeping Harry Potter TV series filming under wraps by using production codenames and banning mobile phones on set.

A report published by The Sun stated that the HBO show, which began shooting its first season this summer, was originally referred to as "Dark Train," before changing to "Brown Cat."

Messages sent to cast and crew are set to disappear after being viewed once, in order to prevent further sharing of information. On set, mobile phones are banned entirely.

However, the secrecy surrounding the show's production has not stopped the Daily Mail from reporting on a royal visit to the show's latest filming location — in Windsor Great Park, close to the home of William and Kate, the Prince and Princess of Wales.

Last week, the royals visited the set, accompanied by their three children: Prince George, Princess Charlotte and Prince Louis. Together, the family met the show's cast, including new Harry Potter actor Dominic McLaughlin, and watched an evening shoot involving the Harry Potter series' famous Hogwarts Express train riding along a specially constructed track.

"There was only one night of filming there so it really was a magical ticket," a Daily Mail source said. "And as for Louis, he got the chance to ride on the train with the driver. He seemed to absolutely love it. It's the dream for most children to step aboard the Hogwarts Express."

Disgraced royal Prince Andrew also reportedly visited the set last week with his grandchildren, separate to the other royals.

In other production news, staff recently sent a memo to cast members warning them that the Windsor Great Park location was "prone to ticks and horseflies," which can provoke fevers and fatigue. If bitten, the advice was to visit the on-set medic.

Earlier this summer, Windsor Great Park was used as a filming location by Marvel, with top-secret scenes shot for next year's Avengers: Doomsday (including the potentially spoiler-filled return of an old Avengers star).

Harry Potter HBO TV Series Cast and Characters: Who's Confirmed for the Reboot?

HBO's Harry Potter TV series is set to debut in 2027, with a season devoted to each of the seven books. The production will include numerous scenes and characters left out of the previous movies, including Peeves the Poltergeist.

Much of the show's filming has taken place behind closed doors, with production based at Leavesden Studios, near London, where a temporary school has been constructed to cater for up to 600 pupils at peak periods of filming. But some public filming has also been spotted, such as scenes set at London Zoo.

Earlier today, Harry Potter author JK Rowling continued her public spat with Emma Watson, who played Hermione in the films, in response to comments made by the actress last week.

Image credit: Eddie Mulholland/Pool/AFP via Getty Images.