Who is Mrs. Ascott from The Cat Who Went Underground and what is their importance?

Mrs. Ascott is Mildred's clairvoyant friend. She holds a meeting at Mildred's cabin, and when Qwill asks about Clem, she says that Clem is far away and wishes to return but is unable. She also provides Qwill with a message from Joy, his dead childhood sweetheart, regarding danger to his cats and an excavation.