Roberta—also known as Bobbie—is the eldest of the three “railway children” of the novel’s title. She is 11 years old when the novel opens and celebrates her 12th birthday in Chapter 4. She is by far the most fully realized and central character out of the three children.

Bobbie is defined by her deeply sensitive nature and desire to do good for others. She is described as “oddly anxious to make other people happy” (165) and full of “the power of silent sympathy” (165). Bobbie’s persistent instinct to “[try] to help other people” (167) is often a motivating factor for her actions throughout the novel. Bobbie is particularly close to her mother, of whom the narrator jokes in Chapter 1: “Of course, mothers never have favourites, but if their mother had had a favourite, it might have been Roberta” (6). Bobbie is always alert to her mother’s feelings and tries to avoid adding to her strain. She does this by urging her siblings to good conduct, and sometimes seeks to distract them from Mother’s unhappiness, as when she challenges Phyllis to a race to distract her from pestering their mother (191).

Bobbie is the moral heart of the novel, embodying general goodwill and innocence.