Looking for a book...?

I read it many years ago, and cannot remember the title or author. The main character is Lolly Leeds. It is set in England. She is a small child that is tossed into the street in front of a carriage, and the owner (Big Black Jack Something) of the carriage ends up adopting her and bringing her home to his own children. A boy and a girl. Because she was starving before she was adopted, she grows up heavy. As WWI breaks out they are young adults. The brother goes off to war. Lolly serves as a "on field" nurse, and loses all the weight. She ends up marrying the brother, who is killed by the sister in a drunk driving accident. Another character (Brockton Something - named for the two cities in Machusetts where he was dumped at an orphanage) takes the blame for the accident, but the sister (not Lolly) must wait for the jail term to be up and marry him. Unhappy marriage, she was not everything he imagined it would be. She ends up killing herself. Lolly and Brock find each other at the end. Any help would be appreciated!!