The British have come to Montgomery County, and this time they’ve brought their cameras.

British Broadcasting Corp. film crews were on hand in Poolesville and Potomac this week filming “Philomena,” directed by Stephen Frears and starring British actors Dame Judi Dench and Steve Coogan.

The movie, based on a true story, tells the tale of an unmarried Irish woman who gives birth to a son, Anthony, in 1952. According to Martin Sixsmith, who wrote the book the movie is based on, Catholic nuns “whisked away” the baby and sold it to an American couple. Philomena spent decades trying to find the son, who was renamed Michael Hess and served as chief legal counsel to former president George H.W. Bush.

The BBC spent two days filming scenes in St. Paul’s Community Church on Sugarland Road in Poolesville.

Caroline Taylor, a consultant who helped the church coordinate with the film producers, said, “I thought it might be Cable Montgomery,” when she first heard a film company wanted to use the site in a movie. She said she thought that perhaps the church, which has a rich history as the center of a freed slave community whose descendants still live nearby, would be part of a documentary.

Then she heard it was the BBC, and thought, “Holy cow, they’re making a full motion picture,” she said.

For the filming in Poolesville, the crew had to transform the historically Protestant St. Paul’s church into Catholic St. Anthony’s.

Gaithersburg resident Gwen Hebron Reese, trustee of St. Paul’s and an extra in the movie, said that she didn’t realize how big a production the whole thing would be at first.

“I’d heard of [Judi Dench], but I’m not a movie person. … I’m more of a book person,” said Reese, who grew up in Poolesville and now lives in Gaithersburg.

Of meeting the Oscar-winning actress — famous for her roles as M in the James Bond movies and Queen Elizabeth I — she said, “it was pretty awesome,” adding that the British star was “very nice, polite and pleasant.”

Two days before shooting started a production crew arrived to make the church resemble a Catholic one. The crew built a confessional, repaired the church’s bells — which had ceased to function (the result of a broken rope, Reese said) — and brought in a font to hold holy water.

“Apart from the movie and meeting Judi Dench and the other actors, that was one of the highlights for me,” she said.

“To walk into the church knowing what it was [before] … and seeing the transformation of the church, it was absolutely beautiful,” she said.

Dolores Milmoe helped set designers transform the church. Milmoe, a Catholic who lives in Seneca, visited the church and helped identify items like statues of Mary and Joseph, the 14 Stations of the Cross, a sanctuary candle and other elements needed to make the church appear like a real Catholic place of worship.

It was a convincing transformation, she said.

“One of extras who stood in for Judi Dench came in and genuflected, got in a pew, and turned to me and said, ‘Is this still a consecrated Catholic church?’” Milmoe said.

Milmoe said she responded to the extra, “‘It’s not a Catholic church … I guess we did the job [well].’”

Reese’s ancestors lived on land around the building.

“If one were to come back, it would just amaze me what they would say,” she said, of seeing the little church in such a big film.

Filming shifted from Poolesville to Sts. Peter and Paul Antiochian Orthodox Christian Church on River Road in Potomac on Thursday and Friday, delaying traffic. Police were on the scene but there was no official road closure, according to Lucille Baur, public information officer for Montgomery County police. The filming was scheduled to continue through 6 p.m. Friday, she said.

Interview requests by The Gazette at the set were declined. A location manager at the church said filming had been slowed by Hurricane Sandy, but that once it wrapped up Friday, the production would return to England to continue work.

Filming also took place in a Potomac house built in 1820 by Thomas Levi Offutt. The house was later sold to Capt. John McDonald, a Civil War veteran and state legislator, who was also responsible for changing the area’s name from Offutt’s Crossroads to Potomac.

Diana Conway, the house’s owner, called the whole experience “very cool and interesting.” About 100 people descended on her house during the filming, she said. “They moved enormous amounts of furniture, art, desks … family photos were moved aside.”

“The dogs were quarantined for a day,” she said, adding that her cat fled the premises.