When I next open them, she’s taking a photograph of the dress. She looks at the dress in a way I recognise – the same way that I look at clothes, the combination of an intense gaze and a dreamy half-smile.

It’s no use – I have to ask. ‘Are you a fashion student?’

She frowns as if I’ve offended her. ‘No. Science. I want to study medicine,’ she says sternly, tucking a strand of hair behind her ear. ‘Why?’

I back off quickly. ‘The way you were looking at it, I thought …’

‘Oh,’ she says, cutting me off before I finished the sentence. ‘I’m looking for a prom dress.’

‘Ah! Do you want to try it on?’

‘No.’ She clutches her cross-body bag. ‘I’ve only got eighty pounds to spend, max. It’s just, you know, I might find something like it, now that I know what I’m looking for.’

She has good skin. Well, she would, she’s a teenager. I can imagine her in the dress. Pale, ethereal, pretty.

I want to see her in it; I want her to see herself differently. ‘There’s some movement on the price,’ I say. ‘You might as well try it on. If it doesn’t look good then you’ll know it’s not the style for you.’

‘Oh-kay,’ she says with a reluctant sigh, as if she’s doing me a favour. Which she is.

I disrobe Dolly. This particular beaded dress has no fasteners. It’s heavy and dates from the 1920s, drop-waisted, designed to be slipped on over the head. I point her towards the dressing room and wait.

She steps out a couple of minutes later. The cautious look has entirely gone.

As I’m watching her, she’s watching me, too.

It hangs perfectly on her and she’s tied her hair back at the nape of the neck, giving her an edgy, boyish, Twenties look.

‘Like, I can breathe in it,’ she says seriously, as if breathing is usually an added bonus where style is concerned.

‘It’s the shape. You look confident.’

‘Well, I am confident. We get taught self-esteem in assembly.’

‘That’ll be it, then. Turn around.’

She turns slowly and really, it’s such a delight to see her wearing it – barefoot, her shoulders back, her head high. Wearing it, as opposed to being clothed in it; there’s a difference. ‘It could have been made for you,’ I tell her.

She goes back behind the screen to change, and she comes back with her hair loose over her grey sweatshirt and the dress in her arms. She holds it out to me. ‘Thanks, anyway,’ she says diffidently.

‘You can have it for eighty if you want it,’ I say suddenly.

She looks at me warily. ‘But that’s almost half price.’

‘It’s never going to look as good on anyone else as it does on you,’ I point out.