ABC's "20/20" - 2013 [Getty Images]

20/20 - "Mysteries of the Castle: Beyond Downton Abbey" is a behind-the-butler look at the Downton Abbey world from inside the real-life English castle that inspired the cult series. A nchored by Amy Robach, "Mysteries of the Castle: Beyond Downton Abbey," a Special Edition of 20/20,airs on THURSDAY, DEC. 26 (9-11pm., ET) on the Walt Disney Television via Getty Images Television Network. (Photo by Hazel Thompson/Walt Disney Television via Getty Images)
AMY ROBACH

Walt Disney Television Hazel Thompson