Two big yellow signs posted on South Main Street recently had the acronym TSOT, but little else to let folks know what was really going on: Hollywood was here!

American A-lister Jennifer Garner and British actor Ricky Gervais of "The Office" fame were in the house — or more accurately in a mansion on Regency Ridge.

They were shooting scenes for their new movie, "This Side of the Truth" (hence, TSOT), at the end of Regency Ridge, which is off Alderbrook Road.

"It's been crazy with all the traffic, but it has been well-managed," said Diane Cahill, who lives at 17 Regency Ridge, next door to all the filming. "This has been so exciting for our little cul-de-sac."

The signs on South Main, also known as Route 28, hung at the left turn for the parking lot to the ice rink at Phillips Academy and also at Alderbrook Road. With numerous trucks, RVs and cars belonging to extras parked at the PA rink, drivers delivered movie-related staffers to 21 Regency Ridge for filming. More cars and trucks were parked along the neighborhood and a police officer was keeping the vehicles on one side of the street.

"Jennifer Garner is great. She just came over (during the afternoon on Friday, May 16) and talked to us and said 'Hi' to all the kids," said Cahill who invited friends over on Tuesday, May 20, and planned to set up lawn chairs so they could watch the shooting of the film's final scenes in Andover. "She said she loves filming in Massachusetts because no one bothers her. She said she is comfortable here."

Gervais, the star of the original "Office" television show that is a big hit in his native England, was less visible on the Andover set. Production crew members said he was in Andover on Friday, May 16, but was busy filming.

Gervais is involved with producing the U.S. version of "The Office," one of NBC's most popular situation comedies for the past several years, according to his Web site. His voice overs can be heard in episodes of "The Simpsons" and "Alias," which also starred Garner.

The Hollywood crew and all its gear arrived at Regency Ridge on Thursday, May 15 and was scheduled to wrap up Tuesday, May 20.

"I think it's great and I'm happy to hear filming was in Andover," said resident Mike Pingree, an extra for several movies filmed in the area. "I would say that tax benefit (for movie productions filmed in Massachusetts) is working like a charm."

Pingree has a scene in "This Side of Truth" that was filmed in a Lowell bank last month. The movie, a romantic comedy about a town filled with people who do not lie, also had scenes shot in Haverhill. It is expected to hit the big screen in 2009.

Finding Regency Ridge

Alec Hammond of Los Angeles is the production manager for the movie and said he needed a mansion for some scenes. Using "Google Earth" and working with a site-location company in Lowell, he found mansions with big yards in Andover.

He said a swooping driveway, preferably with an iron gate, and an inground pool were must-haves. A location scout was sent to Andover. The mansion at 21Regency Ridge, which town assessment records show was built five years ago on 2.27 acres and is now assessed at $3.2 million, met the criteria.

"We didn't want a mansion that screamed New England," Hammond said. "This mansion is great because people all around the country will see it as just a mansion.

"It's got the driveway we needed and has the gate, so we didn't have to build one, so that was good," he said. "There's lots of space in the yard and inside."

Hammond does not know the homeowners, who moved out for the duration of the filming. He said they were paid a standard rental fee for their property, which he did not disclose.

Tiffany Kinder of Boston and formerly of Los Angeles, the film's location manager, is the one who came upon Regency Ridge.

"I knew what they wanted and was just driving around Andover looking for it and I found it," she said.

She took pictures of the mansion, met with movie representatives and everyone agreed on the Andover location for the shoot.

The scene in Andover is about the lead character living at the mansion while fans of his camp out on the lawn in tents. Their "I love you" messages, letters and numerous flower arrangements decorated the driveway gate for this particular scene.

Why so much lights, cameras, action?

Nick Paleologos, executive director of the Massachusetts Film Office, said the state's new tax credit law, enacted in 2006, is what's making the state so hot for films. Filmmakers and studios can get a 25 percent tax cut on their spending in the state. They also are eligible for sales-tax exemptions.

"Keeping up with the demand of hiring workers, like hairdressers, carpenters, make up people, for all these sets where filming is happening, has grown tremendously for us," Paleologos said.

He called the film-location-service growth "unprecedented" and noted that such tradesmen have "doubled their salaries" as filming in Massachusetts has boomed.

Paleologos' figures show that just one movie ("The Departed") had scenes filmed in the Boston area during 2005, generating about $6 million in new revenue for the state. Now, three years later and with the new tax credit law on the books, eight movies, including "This Side of the Truth," are being filmed in the state. Paleologos said filming all those movies will bring in about $380 million for the state.

"That's everything — taxes paid, services received, all that," he said.

Paleologos is optimistic that next year will be even better.

As for Andover, the town is now on the state's "film-friendly community" list and just might get another slice of that very green pie.

"We're a celebrity culture, there's no getting around it. It's gloomy out there with gas and oil prices so high ... Making movies is fun and makes people feel good," Paleologos said. "Maybe another movie will land up there."

Andover attractions

Jennifer Garner and Ricky Gervais aren't the first celebrities to hang their hats in Andover of late. The hometown of Jay Leno and Michael Chiklis made way for Fonzie (actor and author Henry Winkler) on Mother's Day, while esteemed cellist Yo-Yo Ma, actor Alan Alda and Patriots head coach Bill Belicheck have all been in town recently.