The argument was, rather humorously, over a pair of pink Converse. As Beatrice describes it, Fergie instilled in her and Eugenie this sense that they always had each other and needed to prioritize that. This meant that, when fights arose, she pushed her daughters to be really open—“everything was on the table,” even when it came to silly childhood fights “like whose Converse trainers were the right size,” Beatrice shares.
“I remember that fight,” Eugenie responds in the episode. “It was a big one,” Beatrice goes on. “And mum just jumped into that fight. [It was] probably [like] watching a boxing match or something.” (Earlier in the chat, Beatrice explains that, together as sisters, they are both pretty fiery.)