TV’s most famous earl is in Jerusalem to film a documentary on the final days of Jesus.

You wouldn’t expect Robert, Earl of Grantham, to have much to say about the last week of Jesus’ life, but Hugh Bonneville isn’t the earl, although he played him so compellingly for years on Downton Abbey.

Bonneville, it turns out, has a keen interest in the history that inspired the New Testament, and is in Jerusalem to film a documentary, Countdown to Calvary, about the days from Palm Sunday to Good Friday.

“I always found it a really fascinating jigsaw puzzle that I could never fully resolve and I was a really lazy student, too busy doing plays,” he said at a press conference Thursday at the Tower of David Museum.

The television documentary will air next Easter, in 2018, and is being co-produced by RTÉ, Ireland’s national broadcast network, ARTE and APT.

Bonneville, who in person is just as charming as the fictional British nobleman he turned into a household name but more playful and irreverent, has spent the past week touring Jerusalem and the surrounding area. He has traced the movements of Jesus in his final days and has even walked much of the pilgrims’ route into the Old City, starting from Wadi Kelt.

Although Bonneville was here briefly on a backtracking trip in 1983, he considers this his first real visit and is very much enjoying it. Seeing all the sites he had only read about has taught him quite a bit.

“There are these phrases about going up to Jerusalem,” said Bonneville. “You realize it really is what you do, and [it’s]obvious to those who live here. It brings it to life… It’s amazing how small the Old City is, and how big the Temple was. The scale and then the implication of destruction and how cataclysmic it was to Judaism and its beating heart, and how that affected Christianity,“ he said. “It’s been really interesting to see the skullduggery of it, the spies… to get a real sense of drama and, of course, as an actor, I’m a real sucker for that.”

He has also been interviewing experts on the life of Jesus and the history of this period. These authorities include Professor Emeritus Ronny Reich of the University of Haifa; Prof. Paula Fredriksen of the Hebrew University of Jerusalem; Fr. Gregory Tatum of the Ecole Biblique, Jerusalem; Amit Reem of the Institute of Archaeology at Hebrew University; Prof. Helen Bond of the University of Edinburgh; and Prof. Zuleika Rodgers of Trinity College Dublin.

“I’ve been able to ask really stupid questions of really clever people,” said Bonneville. In spite of his modesty, Bonneville clearly has an excellent grasp of the history of this period. He said he was fascinated by everything he had seen in Israel so far, much of which has moved him.

“I went to university an atheist and came out an agnostic,” he said, when asked about his faith. Being in Jerusalem, “you can’t help being aware of the nexus of the three religions” that consider the city holy ground, he says.

The documentary is intended to highlight the “political intrigue” behind the biblical story, according to the executive producer, Ray Bruce. “It’s really a political thriller,” one in which “the city itself is the star.”

But of course Bonneville is also very much the star, albeit an unassuming one. Asked whether he had been recognized during the trip, he said, “Luckily, I haven’t got a Labrador by my side, so I’ve escaped unnoticed.”

Although that may not have been accurate – there are a lot of Downton fans in Israel, plus little kids who know him as Mr. Brown from the Paddington film and movie lovers who remember him as Hugh Grant’s friend in Notting Hill – it was clear that he is a down-to-earth, working actor and history buff.

Asked whether he has a new appreciation for the Monty Python film The Life of Brian, about the same period, he said that film had gotten a lot right, “in terms of the atmosphere and the culture.”

Another way this experience has changed his perspective is that it has increased “my respect for archaeologists and their chiropractors.”