The following note was pinned to my headboard when I woke up on the morning of my ninth birthday.

‘Desirable residence of arboreal elegance now available for immediate occupancy.

The ideal refuge from annoying little sisters and great aunts with sloppy, wet kisses.

Fully equipped with beaten up old armchair, rickety table, storage cupboard and camp bed.

Overnight stays by prior agreement with either parent.

Happy Birthday son!

Love Mum and Dad.’

I ran to the window, and threw back the curtains. There, in the old oak tree near the bottom of the garden, was my new treehouse. I don’t know how Dad had managed to build it so quickly, because it had not been there the previous evening when I went to bed. But that didn’t matter; it was there, and that was the important thing. I had been pestering him for months to build it, ever since I saw the old photograph. It showed him as a young boy sitting in a treehouse in the very same oak tree.

“What happened to it, Dad?” I asked.

“Oh, I grew out of it, and it started to fall apart, so your granddad took it down.”

“Can you build me one, please?”

“Well now, I’m not too sure. It’s not an easy thing to build. I’ll have to talk with someone first.”

I was a little confused by his answer. Dad’s hobby was carpentry. He had made half the furniture in our house, and built both the sheds in our garden. Surely he could build a treehouse? I didn’t let the matter rest, and kept on asking when he was going to build it, but always there was the same hesitancy and a vague ‘we’ll see’.

Finally, he had done it. I quickly dressed, and ran down the garden. A rope ladder was hanging from the doorway.  I climbed up, and used thepiece of string attached to it to haul it up out of anybody else’s reach. All my birthday presents were on the camp bed, and there was some breakfast laid out on the table. I spent the whole morning in the treehouse, and would have stayed there all day if Mum hadn’t made me come down.

“Come on, it’s time to get ready for your party,” she said.

In the excitement of finding the treehouse I had forgotten all about my party. It was being held in the local burger restaurant.

“Can I sleep in the treehouse tonight?” I asked.

“Yes, you can. Now get yourself indoors, and wash and change.”

I enjoyed my party, but all the time I kept thinking about my night in the treehouse. As soon as we arrived home I headed straight out into the garden. Dad gave me a walkie talkie, just in case, but I was confident I wouldn’t need it. I laid my sleeping bag out on the camp bed, and settled in to start reading one of the new books I had received for my birthday. I fell asleep before reaching the end of the first page.

I woke up with a start. It was still dark, but the treehouse was lit by my torch, which I hadn’t turned off before falling asleep. There was someone sitting at the foot of my bed. He was smaller than me, but looked a lot older. He had large pointed ears, and a long pointed nose. He was smiling, and I could see that his mouth was full of pointed teeth. He was dressed completely in green, including his hat. Despite his appearance, I was not afraid of him.

“Who are you?” I asked.

“My name is Twigger,” he replied.

“What are you doing in my treehouse?”

“What are you doing in my tree?”

“Yourtree?”

“Yes, I’ve looked after this tree for nearly three hundred years, since it first sprouted from an acorn.”

“You’re telling me you’re three hundred years old?”

“Oh, I’m a lot older than that,” said Twigger. “This is the fourth oak tree I have been acting a guardian to. Before that I was the guardian to several other trees, but I prefer the oaks, they are so majestic and mysterious.”

“So what are you, and what does a guardian do?”

“I’m a tree sprite. Every tree has its own tree sprite. We try to make sure no harm comes to them. We keep an eye on every creature that lives in the tree, or comes to visit. A tree like this one can be the home to hundreds of different animals and insects, and they all have to show respect for it.”

“Including me?” I said.

“Including you. When your dad asked me to help him build this treehouse, I told him we would be having this little chat.”

“You know my dad?”

“Of course. We met when he spent his first night in his treehouse, the one you saw in the photo.”

“So why did he need your help to build it?”

“Because he knew the most important thing was to make sure no damage was done to the tree. There could be no nails banged into the branches, or bits of rope tied round them and constricting their growth. And, most importantly, it had to be built without any branches being removed.”

“Did you help granddad build dad’s treehouse?”

“Yes, and many more before that.”

“But how can it be built without nails.”

“Because it’s part of the tree, just like any of the branches. The tree is holding it together, and will continue to do so for as long as you want to continue using it. When you stop visiting, the treewill let go, and it will start to fall apart.”

“Just like dad’s treehouse.”

“Yes. Now, there are some other things you need to know if you want to continue visiting my tree.”

Twigger talked for another half hour, telling me all about the history of the tree, the living things that inhabited it, and how I should behave when I was in the treehouse. I must never leave any litter, or carve my initials in the bark, or light matches.

“Remember, if you look after the tree, it will look after you,” he said. “Now, I must be away. I’ve a troublesome squirrel I need to deal with.”

“Will I see you again?” I asked.

“You certainly will if you don’t behave yourself. But anyway, I’ll pop in from time to time, to say ‘Hello’.”

As soon as he had gone I picked up the walkie talkie. Dad answered it immediately, as if he had been expecting me to call.

“Twigger says ‘Hi’,” I said.

“I believe he’s given you his little chat. Well, you mind and remember what he said. Now, how about letting me get some sleep? Goodnight.”