Who is Mildred Hanstable from The Cat Who Went Underground and what is their importance?

Mildred Hanstable is one of Qwill's friends. She is also Roger's mother-in-law. Mildred lives in Mooseville where she is employed as a school teacher, writer for the local paper, and fundraiser for the hospital. Qwill spends a lot of time with Mildred, and she feeds his cats when he is hospitalized.