https://www.amazon.com/Past-Tense-Love-Elizabeth-Cadell-ebook/dp/B06XT51C2D:
The Mostyn world was small and self-contained. The Mostyns themselves were placid, undemanding, without curiosity or malice, totally unconcerned with world trends. Only two members of the family had ever broken free of the Mostyn stream. The first was Madeleine, who, at the age of eighteen, had performed the un-Mostyn-like act of leaving home and vanishing without trace, reappearing just once to bequeath her two infant daughters back into the Mostyn fold. The second was one of those daughters, over twenty years later. Kerry, intelligent and high-powered, now lives in London, earning her living working for ill-tempered tycoons nobody else will work for. Her independence and sense of freedom are distinctly not family traits; neither is her reluctance to marry the eligible, uncomplicated man in her life. But when she is suddenly sent off to France on a mysterious errand by her present irate employer, Lord Hazing, her entire future is changed by a serious of strange meetings and coincidences, not in the least of which echo back to the Mostyn past.