During breakfast the morning after the murder, both of the Americans were confused as to how the breakfast was supposed to be served. Both Morris Weissman and Henry Denton expected to be served, and were surprised to learn that they were expected to provide for their own tray from the buffet table. Now, how could that be? Surely they must've learned by now how breakfast was served?And the answer is, the party hadn't been served breakfast together in that manner at all before that time, in spite of that being their third day at Gosford Park.They arrive at mid day during the first day. They are served tea in the sitting room, then dinner during the evening. The morning of the second day, the ladies are being served breakfast in their beds, while the men are already out for the shoot. Instead, they all participate in an elaborate lunch outdoors in the Greek rotunda. On the evening after the dinner that day, the murder takes place. Thus, breakfast the third day is the first breakfast that are served together in the dining room. And that's when the Americans learn how the breakfast is served.
During the evening of the second day at Gosford Park, the host Sir William McCordle was poisoned to death and then brutally stabbed from behind. So, whodunnit?Mrs Wilson, the head housekeeper, is the murderess. After the scandal during the dinner, Sir William withdrew to his study. Mrs Wilson offered him a cup of coffee, which she had poisoned beforehand. He refused the coffee and knocked it to the floor and ordered some whiskey instead taking a big drink and finds it horrible tasting. Being the faithful servant and prepared for all eventualities, as always, she had brought the poison with her, and quickly poisoned the whiskey before handing it over to him.Meanwhile Robert Parks, valet to Lord Stockbridge, had made plans of his own to murder Sir William. He did this during the evening, when the entire household was listening to Ivor Novello entertaining the guests. Parks had stolen a kitchen knife the night before, which he had hidden in the sand bucket used in case of fire near the service entrance. During the evening, he "went out for a smoke", made use of a couple of dirty shoes to make it look like the assailant came from outside the household, picked up the hidden knife, opened the secret door to the study, and stabbed Sir William from behind but he was already dead from the poison.Robert Parks had been brought up in an orphanage. He and some other boys broke into the office and stole their files which contained his birth certificate and listed his father as unknown and mother deceased. Though, after some investigative research, he had found out that Sir William McCordle was the one that had delivered him to the orphanage. From this he drew the conclusion that Sir William was in fact, his father. He wanted Sir William dead, as a revenge for his mothers death, and for his upbringing in an orphanage.Unbeknownst to him, his mother was not dead at all, but alive and well and working in Sir Williams household having changed her name to Mrs Wilson. Mrs Wilson had understood the true meaning of Robert Parks upbringing. That he had not been given to a good family that Sir Williams knew but had been dumped in an orphanage and that he was in fact, her son, and that he was there to kill Sir William. In an act of anticipation and true self sacrifice, she killed Sir William before Robert Parks had the chance, to save her son from the gallows and giving him closure at the same time.It is still an open question if Robert Parks ever figured out the true relationship between him and Mrs Wilson, it is however clear that she knew that he was her son.