Diamonds in Danby Walk by Pam Evans

If Ralph Jackson had not been selfishly intent on an afternoon's stolen pleasure with his East End mistress Clara that day in 1900, a great many lives would have been different - most notably that of Amy Atkins, Clara's skinny young niece. Her penniless father George wants a better start for her than the mean streets of Bethnal Green, and if he has to resort to a spot of blackmail to get it, so be it.

For fear of his philandering ways coming to light, Ralph offers Amy a job at his posh West London jewellers. With her quick wits and eye for business she attracts the attention of Ralph's handsome son Clifford. But when one thing inevitably leads to another, weak-willed Clifford is quite happy to leave Amy holding the baby. He has reckoned without the powerful influence Amy's father still exerts over Ralph. An amazed Amy finds herself Mrs Clifford Jackson, but even love and gratitude do not blind her to her husband's weaknesses, and when tragedy strikes she is faced with some difficult choices...