Generally, Beryl Bainbridge seemed like a very nice person, who apparently worked as a professional theatre reviewer without ever giving a bad review. It's my guess that she took rejection hard, since a romance gone very bad and a detail from her own autobiography seem to coincide in this book.
She achieved great success and a loyal readership it's said, with historical fiction such as this, yet the setting need not have been the Titanic at all to write a kind of parlour plot for the working class.
I would not have missed that unforgettable story of a lost romance or the description of those on the ship during the exact moments it is sinking, but it seems, along with a noticeable but justifiable sneering at upper class decadence, that she seems unwilling to upset the enclosed atmosphere of her boat-parlour by looking deeply into her characters as a self-centered class.