But soon, pregnant Sybil and her husband Tom arrived. "Please tell me you sent the money," Sybil says to her father, Robert, but he was nonplussed; he’d done no such thing. (In a truly touching later development, it was revealed that Violet had sent the money to enable them to make the trip.)
But not everyone was happy Tom was there, and during one dinner, a snobby neighbor named Larry Grey slipped something into Tom’s drink that made the Irishman act drunk and start loudly spouting his politics. When caught, Larry couldn’t see what the fuss was all about. “He’s only a grubby little chauffeur,” he remarked. Robert, Larry’s father, Lord Merton, and Matthew all stood simultaneously, ready to defend Tom, but it was Matthew who went over to Tom and announced that his future brother-in-law would be his best man as well.
And even more drama was brewing before the actual wedding between Matthew and Mary could take place. Robert went up to London to look into financial matters and discovered that railway investments he’d made before the war had gone badly and wiped out most of his wife Cora’s fortune. If something didn’t happen to save them, the Crawley family would have to give up Downton Abbey.
Mary was aghast to hear the news, but thought she saw a solution when Matthew received a letter informing him that he was in line to receive an large inheritance from the father of his former fiancé, Lavinia, who died of the Spanish influenza. When it was discovered that the first two heirs were dead, it seemed all but certain Matthew would receive the money, and Mary told him it would solve all the family’s financial problems. Matthew, however, was stubborn – he said that because he had been named as the heir for his relationship with Lavinia, he couldn’t use the money to save his new fiancé’s home. (This seemed a little convoluted and over-dramatic, much like Matthew’s certainty last season that he and Mary could never be together because their love had caused Lavinia to die of grief, but I recognize the show needs some problem to keep tension between the couple.)
Mary told Matthew that his unwillingness to save her home made it clear he wasn’t on their family's side and fled the room, an act witnessed by sister Edith.