The Charmed Heir by Merry Farmer

Mistaken identity is only the beginning….
Miss Charlotte Benning has lived a charmed life as the daughter of a wealthy, eccentric industrialist. Her only aim in attending the house party at Nedworth Hall is to find a nice man to marry and have a family with. She certainly doesn’t think she’s witty or clever enough to engage in all the excitement about Lord Carshalton’s mysterious heir.
But there are things about Charlotte’s father, and her origins, that even she doesn’t know….