The top secret wedding ceremony was filmed at the village church in Bampton, Oxfordshire in July (15) and after the shoot was over, a member of the public found the mocked up paperwork, including the order of service, opening prayers and vows, which reveals the shock plotline.

"The cast and crew have gone to great lengths to hide the storylines. It seems a bit ridiculous that security measures could be put in place then someone just leaves an order of service lying around," a source tells Britain's The Sun newspaper.

The wedding is said to be in addition to the upcoming nuptials between butler Mr. Carson, played by Jim Carter, and Phyllis Logan's housekeeper character Mrs. Hughes.