Big sister, little sister
Charlotte Higgs - the quietly confident and happily boring eldest Higgs girl - found herself in an unusual frame of mind. And that frame of mind consisted mainly of a determination to drink a large (for her) amount of the alcohol provided by her parents, hang-over be damned, while frowning severely in the general direction of London.
The metronomic tap of the fingers of her free hand against her thigh was a clear sign to those who knew her that the source of unusual behavior was irritation. A great big heap of irritation not usually found in even tempered Charlotte.