Well, she wasnt a widow when she died. And she has a London home address (albeit a hotel) even though she died in Sussex.
Getting a copy of her Will might give you some help, to see who she left bequests to.
Probate index entry
Jane Hannah St Quintin of the Alexandra Hotel, Hyde Park Corner, Middx, (wife of William Brandon St Quintin esquire) died 3 Jan 1897 at the Queens Hotel Hastings Sussex. Probate to Friend Lewin esquire and Nathaniel Stevenson Liuetenant general in her Majestys army. Effects £7667 14s 10d