Sunshine and Shadows by Katie Flynn

Daisy Kildare lives with her family in a cottage perched on the Connemara coast. 

The Kildares are poor but happy. But when their croft is wrested from them, Daisy's Aunt Jane, who is housekeeper to Dr and Mrs Venables, offers to take Daisy back to Liverpool so that the child can be a companion to her employers' orphaned niece, Cynthia.

Daisy is a tomboy, young for her age, self-willed and hot-tempered. In Ireland she was seldom in school but often in trouble. Now, however, she tells herself that she must conform. She begins to work hard in school, and though she and Cynthia don't get along, she meets Jake, the chauffeur's son, and life in Liverpool becomes easier to bear.

When Jake goes to university, Daisy means to follow suit, but war intervenes and instead, she starts work at a munitions factory, and falls in love for the very first time.