Meanwhile, Edith struggles to cope with being parted from her baby daughter, and it seems to be only a matter of time before her emotions get the better of her and the truth comes out.
According one of the show's stars, Hugh Bonneville, one of its great assets is its wonderful cast. "I may be The Daddy of the house but it's an ensemble show; the whole thing is a giant set of interlocking cogs, all vital in driving the engine of the house and, therefore, of the show."
It's rumoured that at Christmas, an even bigger star will be joining in – Bonneville's Monuments Men co-star George Clooney has supposedly already filmed several scenes.
Although the regular cast aren't Hollywood A-listers yet, they have had a small taste of what it's like to be hugely popular thanks to the programme's success.
"I think it's fair to say that some people have become obsessed with the show, which is a nice problem to have," says Bonneville.
"Clearly it's gained a place of affection in lots of people's hearts – and that's great. It's thrilling to be in something that seems to have brought large numbers of the viewing public together in shared enjoyment."
Donwton Abbey is on ITV1 from 9pm.