Who is Jane Smith-Ellis from Stern Men and what is their importance?

Protagonist Ruth Thomas' maternal grandmother, Jane is abandoned as a newborn in 1884 at the Bath Naval Orphans' Hospital and adopted in 1894 by young Dr. Jules Ellis to serve as his only daughter's companion. Jane in fact becomes Vera's lady-in-waiting. Jane is big, shy, and accommodating, accompanying Vera everywhere but, as a legal relative, is paid no salary for her efforts. In 1925 Jane becomes pregnant at age 41.