Yes, Simon Williams' suicide was shattering and very unexpected. But the scene that tears at everyone's heart, is the very last one...Rose leaving, for the last time and then looking back, over her shoulder, on very last time.
haven't seen Upstairs/Downstairs in many decades, but now that you mention it...yes, the end was right out of Turgenev! Brilliant critique!
The final episode is heartbreaking. Poor Rose, walking through the empty house, listening to the voices of all her long-gone friends. And having lost all her dead fiance’s money through James’ stupidity! Wow.