Harry’s logistical wizard

DURING World War II, the aerodrome in the middle of the empty fields near the city of Watford was used to produce the fighter planes that Winston Churchill craved. When peace came, Rolls-Royce took over and used the site to make airplane engines.

But Britain’s industrial might has faded quite a bit since then, and the old plane factory and airfield with its extensive grounds has been taken over by a new enterprise based not on Britain’s fighting power and engineering skills but on the ingenuity of its artists, particularly one J.K. Rowling, author.

It is now home to Leavesden Studios, where the 12-months-a-year task of producing the Harry Potter films is executed by hundreds of people working full time to bring Rowling’s vision to the screen. At any given point at Leavesden, marketing plans for one film, shooting for the next and casting choices for the one after that are in progress at what is in effect a Harry Potter factory in a distinctly unglamorous setting about 30 miles outside London.

In other words, this is a franchise operation going at full tilt, with the latest result, “Harry Potter and the Goblet of Fire,” the fourth of seven highly anticipated films, opening nationwide Friday.

In the midst of this three-ring-circus environment, producer David Heyman serves as central troubleshooter. And watching Heyman at work offers an apt portrait of modern, high-wire filmmaking.

On one typical day, Heyman met with his visual effects team to suggest improvements to several sequences and to try to talk down the budget, consulted with costumers about the outfits and makeup Ralph Fiennes will wear as the evil Lord Voldemort, talked to director David Yates about the schedule for the next Harry Potter film, hassled the screenwriter about a problem in the current one and approved publicity photos.

“It’s a marathon,” Heyman said.

The “Goblet of Fire” shoot was scheduled for 161 days, taxing everyone’s stamina. Heyman said the time restrictions on the three child stars -- Daniel Radcliffe (Harry), Emma Watson (Hermione) and Rupert Grint (Ron) -- are the main reason the films take so long to complete: Strict British laws governing the use of child labor limit the time spent on the set by underage actors to 4 1/4 hours per day.

This frees up a lot of time for the individual tutoring that has replaced the traditional high school experience for Harry and his Hogwarts cohorts but places formidable limitations on the producer and this installment’s director, Mike Newell.

The children, though, aren’t the only ones whose schedules provide logistical challenges: Formidable stars such as Fiennes, Maggie Smith, Gary Oldman and Miranda Richardson must be shuttled in and out with precision to accommodate their other projects.

But those are just a few of the reasons for the slow pace. The mix of computer-generated effects and live shoots takes a tremendous amount of time to coordinate, and the fantastic nature of the plot poses substantial hurdles, says Stuart Craig, the Academy Award-winning production designer who was handling his fourth Harry Potter film.

“The way the story is structured, Harry has to undertake these three major tasks, and they are so enormous in their scope and ambition that you cannot build conventional sets that contain the whole action,” Heyman says. “One is underwater, one is fighting a dragon flying over the Highlands of Scotland and one is in a maze that fills a valley in Scotland and then transfers to a cemetery. None of these things are achievable on a soundstage.”

HEYMAN’S involvement with the Harry Potter enterprise stems from the good fortune of having a perceptive secretary who scooped the first book, “Harry Potter and the Philosopher’s Stone” (its British title), off the “low priority” shelf for his perusal. Heyman recalled that he didn’t like the title but devoured it in one sitting. The next morning, he was lobbying Warner Bros. executives to buy the property.

“I had no idea that the book would become the phenomenon it did,” he says. “Not a clue. But it was a book I liked. What did I fall in love with? The author’s voice was the first thing; every sentence is very alive. Two, it didn’t talk down to kids. And Harry as a character really appealed to me: He was an outsider, an orphan who wants to belong, and we all want to belong. And he finds at Hogwarts the home he never had. That really touches a chord. The core values are loyalty and friendship and trust and courage. And the books made me laugh.”

To win the author over, Heyman promised J.K. Rowling, or Jo as he calls her now, that he would be faithful to the story and the characters. That became easier when the books became a global success of previously unimagined proportions, making Rowling one of the best-loved and wealthiest authors in the world.

Which brings us to what might be Heyman’s most important role: Because Rowling serves as the ultimate authority when there are questions of substance on the film, Heyman consults her regularly to discuss changes and to seek her advice.

“She knows these characters inside out, and she knows what is going to happen in the books to come,” Heyman says.