When you first see Lucy talk to the great oak tree in the school's backyard, you give the little girl a letter, folded in perfect thirds, and say: "Please give this to your mother, my dear."

Lucy cooks her head, as if there was something curious in your speech, then she smiles, a patchy kid smile, gaps between her little teeth and she nods. "Yes, Miss Johnson", she says and caresses the oak's bark.

The next day, she gives you a letter from Helen Pevensie, in letters that look almost painted. She's a child, the woman writes, she's small and a girl, too. You send little Lucy to her seat, next to the girl she bonded with so beautifully before the bombs started falling, and you wonder idly if she treats her boys the same, if her response had been the same, had you talked about her eldest.

"I don't understand them", Lucy says and you hesitate, your hand hovering over her shoulder. "They are all so strange here, always touching, always lying." She runs her hand over the bark. "Mother took my knife. Edmund said to take it back but I cannot reach the drawer and all the others are away."

"Lucy", you say. "Lucy, who are you talking to?"

Little Lucy turns around and laughs. "I'm playing", she says. Then she leans close to you. "I'm pretending there's dryads in the trees."

You hum and lead her inside. It must be the country. They all came back different from the country, wilder, almost strangers to their own parents.

"Sometimes", you say, when your mother asks what you are fussing about, "sometimes I think she's a fairy wearing human skin. But then she speaks of talking lions and I think myself silly."

She doesn't react to her name, sometimes, stares out of the window longingly as if she didn't belong within walls and you stop calling on her and write another letter. She's distant, you write, she's distant and I am worried that she thinks of too many adult things, sometimes.

Helen Pevensie answers, in that unsettlingly perfect writing. She is just a child, she writes. She's just a child and we are at war. She might remember the bombs.

"Do you like my dress?", one of the girls asks and Lucy hums.

"Oh, it's most wondrous. But it cannot be very comfortable."

The girl furrows her brows. "I want it to be pretty, not comfortable. One's best clothes are never comfortable."

Lucy sits on her desk, legs swaying back and forth. "They can be", she says and grins, her teeth look too small for her jaw.

"I am cold", Lucy says and the wind whispers through the oak's leaves. "Mother sent Edmund Turkish Delight. I wish I could warn him, but I cannot reach the phone, high up on the wall. And letters are too slow." She sits down on the wet grass. "How I wish Aslan was here. His fur could warm my freezing bones."

Your child is miserable, you write, and bend the tip of your pen. Your child is miserable and she's small and cold and homesick for a place that is not London.

She is a child, Helen Pevensie writes, she probably misses the country.

"Mother took my knife."

"Peter says Edmund weeps whenever he sees snow fall softly to the ground."

"I am cold."

"I am so much too small."

"I miss Tumnus and the woods."

"Susan's hair will never grow back. She says it is silly to mourn such a thing but she keeps attempting to braid it and there's never enough of it."

"Mrs Pevensie, I am sorry to bother you", you say when she opens the door. "But I have to talk to you about Lucy."

Mrs Pevensie smiles. "Oh", she says. "Please come in."

You sit on the uncomfortable wooden chair at the kitchen table, a cup of tea before you. "I didn't announce myself and I apologize for that, but I think Lucy is truly miserable without her siblings."

Mrs Pevensie leans against the table and sighs. "I know", she says. "She is as bright and lovely as ever, but something happened on the country that made them all cling to each other for dear life. If she weren't so young I'd have sent her to school with Susan."

The next school year, Lucy's chair is empty and the headmaster receives a letter, much less perfect than any of the ones you've written, informing him that Lucy would attend the same school as her sister Susan.

When you teach future classes filled with girls about fairy tales and myths, you think of an eight year old and her patchy child smile talking to the great old oak tree as if it was a dear friend.