Ok, my latest theory is…
The unhinged heiress (shown in the previous page “We didn’t vote for it”) who is about to be married does not have her diamonds stolen. This sounds positive until you realise she was broke and in cahoots with the thieves for the insurance money. Things spiral after her fiance dumps her and she devotes her life to ‘getting even’ with Lottie – because all spoilt, rich kids need an obsession!