Since the creation of "Downton Abbey" in 2010, historical adviser Alastair Bruce has worked to make the show as historically accurate as possible, from the character's outfits to even the smallest home decor.

However, over the years, many have wondered why the hit PBS show is devoid of any reference to Christianity, as religion would have been a large part of the lives of the aristocracy in the early 20th century.

In a recent interview with The Telegraph, Alastair Bruce, who serves as the show's historical advisor, revealed that those in charge of the series had ordered producers to "leave religion out of it" for fear of estranging atheist viewers.

Ensuring Christianity is nowhere mentioned in the show is somewhat difficult, he said. For example, the Crawley family has never been seen in the process of sitting down to dinner in order to avoid showing the characters praying before their meal.

"In essence you hardly ever see a table that isn't already sat at. We never see the beginning of a luncheon or a dinner, because no one was ever allowed to see a grace being said, and I would never allow them to sit down without having said grace," Bruce explained.

Bruce told the news outlet that he really wanted to incorporate prayers into the show, but all of his suggestions were dismissed by the executives.

"I think that the view was that we'd leave religion out of it, and it would've taken extra time too. I suggested a Latin grace, but they decided that was too far, and no one would've known what was going on," he said.

The show's creators were so determined to remove religion from the series that even table napkins were targeted.

"Everyone panics when you try to do anything religious on the telly," Bruce said. "I still wish we could've got some decent napkin folds, but I was always left with my triangle."

Additionally, in an interview conducted earlier this year,  ITV's director of television Peter Fincham said that the channel had considered renaming the series because it featured the word "Abbey" in the title, which connotates Christianity. 

"I can remember discussions that almost seem comical now," he said. "We talked about the word Abbey. Would people think it would have nuns or monks in it and be a religious series? But we satisfied ourselves they wouldn't and did a bit of marketing around it."

Meanwhile, "Downton Abbey" season 6 is down to its last episode, and this will be the Christmas special. Bruce tells fans that a lot of surprises are in store for them, and the ending will be an unpredictable

"It is going to end in a way that you might not expect. It will be both exciting and emotional and it will leave you thinking lots of things," he said.