In Charn [Jadis] had taken no notice of Polly (till the very...

In Charn [Jadis] had taken no notice of Polly (till the very end) because Digory was the one she wanted to make use of. Now that she had Uncle Andrew, she took no notice of Digory. I expect most witches are like that. They are not interested in things or people unless they can use them; they are terribly practical.