The Adventures of Jane Waterford - Victorian Orphans series, #2

Seventeen year old Jane Waterford quits her step-mother's house in Ireland after the sudden death of her father and takes a ship to England to get away from the threat of an arranged marriage. A friendly widow takes Jane under her wing, but their carriage overturns on the road and after that things never go quite as Jane intended. Unwittingly she takes a job as secretary to the grandmother of the Duke of Grantley, the mysterious stranger who rescued them after the accident.
When Jane at last realises who he is she clashes with him over a number of things, since they are poles apart politically. Little does she know that the Duke is taking more than a passing interest in her developing business, concerned at the lengths she is willing to go to in order to achieve success. Little does he know what Jane will be capable of when she discovers his own subterfuge.