Love your plot summary Le Booof, pretty close to the unlikely "truth" I reckon.
I love DA, but I do wish they'd just slow it all down a bit and let the characters and the story lines develop a bit. It's like a revolving door farce sometimes. Evil ladies maid writes evil letter to evil ex wife of wonderful valet who loves wonderful house maid. Handsome soldier goes to trenches, comes back from trenches wounded, is nursed by beautiful aristocratic girl who still loves him. Evil chauffeur tries it on with beautiful aristocratic girl 2. Evil Captain gets silly housemaid up the duff, saintly housekeeper tries to save her. Oh and that was all in one episode. Soon it will be 1960 and we'll be watching M&M's grandchildren trying to prop up the crumbling Abbey.
I think all those ad breaks are just there so that the plot can move on a few months - a sort of time warp effect.
I haven't lost faith yet, but I think that in series 3 they just need to let us all take a breather and have a lovely wallow in nostalgia rather than be sped headlong through the years.