I look around, then my jaw drops and my shoulders slump in relief.
I'm standing opposite my own house.
Home lies just across the street.
I'm about to run over when I hear a bark behind me. I jump and turn around, and my jaw drops again.
A small girl, about twelve years old, is walking down the garden path of the house behind me, number 6, jangling the front door keys. She's holding a cocker spaniel on a leash, which is barking excitedly and pulling at her lead.
I recognise the girl. Her face is round, freckled and grinning, her eyes are round, grey and magnified by enormous glasses, and her ginger hair is tied back. I recognise her dog too: a young spaniel called Boo.
The girls name is Lola Robertson, and she moved away from this house to live in London. Five years ago.
When she moved, she was thirteen years old.
Slowly, I turn around and look closely at my own house, and I start to notice things I didn't before. The window boxes haven't been painted yet. There's a huge hole in the hedge from that time Adam crashed into it on his bike... a hole that grew back years ago. Most importantly, maybe, is the car in the drive. The tiny old red Ford Anglia that used to be Nikki's. When she moved in with us, she sold that red car to buy a larger one with enough seats for all of us. We kept Uncle Fred's car so he could drive to work early in the morning, and so that we have a spare in case of an emergency.
I've gone back in time.
But I don't know why I'm surprised. After tonight, nothing should surprise me any more. In fact, I probably wouldn't be surprised if you told me that Lola Robertson's dog was actually a thousand-year-old fairy.
Boo pulls Lola out of the gate and starts snuffling around. She wanders over to me and, before I even think of moving, walks right through me as if I'm a ghost, as if I'm thin air, as if I'm not here at all.
Maybe I'm not.
I turn around slowly, watching them walk away, and I see a grey car turn onto the street and start driving down it.
The grey car that still lies on our drive today.
Of course, this version of the car is much less battered. There's no long scratch on the side from the time Uncle accidentally reversed into Mrs Lemon's rose bushes, and it just looks newer. Still old, but newer.
The car parks in our drive and our past selves all tumble out. My heart melts as a little five-year-old Rosie skips into the house holding an enormous stuffed unicorn, giggling. Adam, who must be ten, follows, licking on a lollipop. Uncle Fred and Nikki walk after them, smiling.
After them comes Jack, and he's holding a small, purple cuddly hippo toy. As soon as I see it, something in my brain clicks.
I remember that toy.
I remember this day!
It was maybe the third or fourth time Adam, Rosie and I had met Nikki, and we'd all gone out to a fair nearby. We'd spent the day there, winning prizes and eating ice cream and candy floss, and I remember going into an enormous maze and finding the centre. It was at this fair that Jack won a small purple hippo toy at the Hook-a-Duck.
At this moment, I see the last person come out of the car.
Little, eight-year-old me. Erin walks up to the steps, but instead of climbing up, she sits on the steps, looking quite unhappy for someone who had just had a day out.
I remember that, at the fair, I had fallen in love with a huge pink teddy bear, almost as tall as I was, at some stall or other. I think it was one of those ones where you have to knock over a stack of cans with a ball. But, of course, they game had been built to be almost impossible- the cans were too heavy and the balls were too light to win. I remember Uncle Fred explaining this gently to me after he lead me away from the stall, after my fifth go.
"But why?" I asked. Uncle had to think about that one.
"He wants more money, darling. He wants to make it very hard to win, so that people will pay for more goes. Do you understand?"
I thought about that, and it upset me. Eight-year-old Erin didn't understand, not really. Didn't he want the children to win? Did he want to keep the toys for himself? Why was he stopping the bear from having a nice home?
I watch Erin sit on the steps, frowning, looking at her feet. Then Jack steps out of the door, still clutching his hippo.
"Are you sad?"
Erin jumps and looks at him. He sits down next to her, on the other side of the step. "Because you didn't win?"
Erin thinks for a minute. "Only a bit.  I'm mostly sad at that man."
"Oh."
"But I did want the teddy. More than anything in the whole world."
Jack scrunches up his face, as if he's making a hard decision. Then he holds out the hippo. Erin looks at him in surprise.
"You can keep it if you want," he says. "Why?" asks Erin quietly. I suddenly realise that I've crossed the road and come up the drive, and am near enough to hear every whisper.
"I don't want you to be sad," says Jack simply.
Erin looks hard at the hippo and decides that a purple hippo is much better than a pink teddy. But she hesitates. I remember feeling guilty about taking Jack's hippo when he won it fair and square.
"Let's share it," Erin says firmly, taking by hold of the hippo. Jack's face lights up.
"Really?"
"Yes. You even get to name him."
Jack's face suddenly becomes serious and thoughtful. Clearly choosing names is a serious business.
"Pippo," he announced at last. "Because it's a mix, see? P... ippo. P for purple..."
Erin nods. "That's a clever name."
She shuffles close enough to Jack for Pippo to sit on both of their laps at the same time, and I feel my heart melt all over again.