A film crew has been spotted at Ivinghoe Beacon as residents told the LBO that they have seen medieval tents and knights.
The production team and actors are said to have arrived at the beginning of the week, with filming allegedly taking place in the woods near the Bridgewater Monument.
Photos show that a number of historical tents have been erected on the beacon, although the crew and set is certainly not the same size as the Star Wars production team, which was based at the site in August.
One interviewee, who wished to remain anonymous, said: "I think they have been there since Monday or Tuesday.
"There's a security guard down by one of the footpaths and yesterday they were filming up near the monument, up near the woods.
"All I saw were high vis jackets and security guards but my friends have seen medieval knights and tents.
"I'm itching to know what it is!
"The security guards often won't tell you but it's not on the same scale as when they filmed Star Wars - that felt like a whole city had moved in!"
She added: "I suppose people choose Ivinghoe Beacon because it's near the studios and the A41. It's quite a special area."
Jasmine, front of house staff at Brownlow Cafe, Moneybury Hill, said: "We are not sure why they are filming. They don't tell us!
"They are filming up at the monument in the woods and probably by the house."
The LBO also called The Greyhound Inn, Stocks Road, to see if it could help to solve the medieval mystery, but its staff didn't know why the film crews were there.
A National Trust spokeswoman for the Ashridge Estate, said: "As part of the relationship we have with the production company we are not able to share any details about what is going on."
Do you think you know what is being filmed at Ivinghoe Beacon?