A Nurse was the usual term in the 19th and early 20th century for the position that is now more commonly called a Nanny. The nurse was given almost complete responsibility for the care and nurturing of infants and young children. They were almost always single or widowed women who lived in the family home and often became beloved family friends, returning to look after younger generations when their first charges started their own families.
In Ransome's worldEdit
The Walker family employ a nurse whose current task is to look after Bridget or Vicky as she is known in Swallows and Amazons. Presumably she has looked after the other Walker children when they were younger.