Who is H. from A Grief Observed and what is their importance?

Lewis' wife is referred to throughout the book only as H., a common convention in books of the early 20th century, but unusual in a memoir. Lewis describes her in every way as his intellectual equal, which is high praise from a man as respected in as many circles as C.S. Lewis. She called him on his silliness and held him accountable to clear thinking. She challenged him to live his faith consistently and coherently, and lived hers in such a way that he learned by her example to listen faithfully to the voice of God. He describes her both as a sword, tempered and straight, and as a garden or a collection of gardens, nurturing and giving life to everyone around her.