What is the topic of the book Mr. Mybug is writing and what is Flora's reaction to hearing about it?

Based on three letters he has in his possession, Mr. Mybug is out to prove that the Bronte brother, Branwell, in fact wrote WUTHERING HEIGHTS and the other Bronte novels and was a man of genius suppressed by his drunken sisters. Flora finds it rather ludicrous but humors him to avoid any form of debate.