I assume you are refering to the incident at the beginning of Chapter Fourteen that describes Fall and how Kit sees her uncle in a different light after looking at him out of the house and seein what he does, without him aware of her presence. As she sees the way that he contemplates the golden fields and looks towards the river, and then the way he picks up earth and holds it with "a curious reverence," she feels a kind of solidarity with her uncle, as she sees that he has the same passionate love for the land that she does. Note what she says after seeing this:
Kit backed through the door and closed it softly. She felt as though she had eavesdropped. When she had hated and feared her uncle for so long, why did it suddenly hurt to think of that lonely defiant figure in the garden?
This incident is therefore very important, as Kit, with this sight of Matthew Wood by himself, discovers that she is able to identify with him and that they are, in some ways at least, similar.