I know, I think. I know this place off by heart. But Thea and I just nod, and we follow her direction, sliding through the half-opened door under cover of the sound of clapping. The speeches are already under way, a woman at the podium smiling, and waiting politely for the applause to die down.

I had prepared myself for seeing Miss Armitage, the headmistress in our day, up there, but it’s not her on the dais, and I’m not surprised – she must have been in her fifties when I started at the school. She’s probably retired by now.

But the reality is, in a way, more shocking.

It’s Miss Weatherby, our former housemistress.

‘Fuck,’ Thea whispers under her breath as we make our way around the tables of well-to-do old girls and their husbands, and I can see from her pallor that this is just as much of a shock to her as it is to me.

As we tiptoe around chairs and over handbags, past gilt-lettered plaques listing hockey captains and girls who died in the war, and unflattering oil portraits of former heads, Miss Weatherby’s well-bred tones echo around the panelled hall, but the words pass over my head, unheard. All I can hear is her voice that final day, ‘Isa, this is best for everyone, I’m very sorry your time here at Salten didn’t work out, but we all think – your father included – that a fresh start is the best thing.’

A fresh start. Another one.

And all of a sudden I became one of them, a girl like Thea with a string of schools behind her that she had been asked to leave, with the threat of expulsion over my head.

I remembered my father’s stony face in the car. He asked no questions, I told no lies. But the reproach that hung in the air, as we sped back to a London filled with the smell of hospitals and the beep of monitors, was How could you? How could you when I have all this to deal with already?

Fatima’s parents were still abroad, but a grim-faced aunt and uncle came down from London in their Audi and took her away in the middle of the night as I watched from an upstairs window – I never even got to say goodbye.

Thea’s father was the worst – loud and brash, laughing as if bravado could make the scandal go away, making suggestive cracks as he slung Thea’s case into the back of the car, the smell of brandy on his breath though it was only noon.

Only Kate had no one to take her away. Because Ambrose … Ambrose was already gone. ‘Disappeared before they could sack him,’ said the whispers in the corridor.

All this is fresh in my mind as we make our way, with whispered apologies, to the table marked ‘Pankhurst’ where Fatima and Kate are waiting, their faces full of anxious relief as we slide into our seats, and a final burst of clapping breaks out. Miss Weatherby is finished, and I can’t recall a word she said.

I open up my phone and text Liz under cover of the table. All ok?

‘Vegetarian or meat, madam?’ says a voice behind me, and I jerk round to see a white-coated waiter standing there.

‘Sorry?’

‘Your meal choice, madam, did you tick the meat option or the vegetarian option?’

‘Oh –’ I look across at Kate who is deep in conversation with Fatima, their heads bent over their plates. ‘Um, meat, I guess?’

The waiter bows and places a plate of something swimming in a thick brown sauce, accompanied by bronzed piped potato shapes and a vegetable that I identify, after some thought, as a roasted artichoke. The effect is fifty shades of beige.

Kate and Fatima both have the vegetarian option, which looks nicer by far – some kind of tartlet with the inevitable goat’s cheese, I think.

‘Ah,’ says a man’s voice from my right, ‘this must be a dish in tribute to Picasso’s lesser-known brown stage.’

I look, nervously, to see if he is talking to me, and somewhat to my dismay he is. I manage a smile.

‘It is rather that way, isn’t it?’ I poke at the artichoke with my fork. ‘What do you think the meat is?’

‘I haven’t checked, but I would lay you favourable odds that it’s chicken – it always is at these things, in my experience. No one objects to chicken.’

I slice a piece off the end of the amorphous brown-clad lump and put it cautiously into my mouth and yes, it is indeed chicken.

‘So, what brings you here?’ I say, after swallowing. ‘Clearly you’re not an old girl.’

It’s a thin enough joke, but he has the grace to laugh as if it were not entirely predictable.

‘No, indeed. My name’s Marc, Marc Hopgood. I’m married to one of your contemporaries, Lucy Etheridge, she was back then.’

The name means nothing to me, and for a moment I hesitate, unsure whether to pretend a knowledge that I don’t have, but I realise quickly that it will be pointless – one or two questions will reveal my ignorance.

‘I’m sorry,’ I say honestly, ‘I don’t remember her. I wasn’t at Salten House for very long.’

‘No?’

I should stop there, but I can’t. I’ve said too much and too little, both at the same time, and I can’t stop myself filling in at least some of the blanks.

‘I only came at the start of the fifth, but I left before the sixth form.’

He’s too polite to ask why, but the question is there in his eyes, unspoken, in his eyes as he refills my glass, like the nicely brought up public-school boy he almost certainly is.

My phone beeps, and I look down briefly to see all ok :) :) :) flash up from Liz, and at the same time a voice from Marc’s other side says, ‘Isa?’

I look up, and Marc edges his chair back a few inches to allow his wife to lean across him, her hand extended.

‘Isa Wilde? It is you, isn’t it?’

‘Yes,’ I say, thankful that Marc has already mentioned her name. I push the phone hastily into my bag and shake. ‘Lucy, isn’t it?’

‘Yes!’ Her cheeks are pink and white as a baby’s and she looks jolly and delighted to be here, in her husband’s company. ‘Isn’t this fun! So many memories …’

I nod, but I don’t say what I’m thinking – that the memories I have from Salten House are not all fun.

‘So,’ Lucy says after a moment, picking up her knife and fork again. ‘Tell me all about yourself, what have you been up to since you left?’

‘Oh … you know … this and that. I studied History at Oxford, then I went into law, and now I’m at the Civil Service.’

‘Oh, really? So’s Marc. What department are you in?’

‘Home Office, currently,’ I say. ‘But you know what it’s like.’ I shoot Marc a sideways smile. ‘You tend to rattle around a bit. I’ve worked across a few departments.’

‘Don’t take this the wrong way,’ Lucy says, hacking busily at her chicken, ‘but I always assumed you’d go into something creative. What with your family history.’

For a minute I’m puzzled. My mother was a solicitor before she gave up work to have children, and my father has always worked in financial compliance. There is no hint of creativity in either of them. Has she got me mixed up with Kate?

‘Family history …?’ I say slowly. And then, before Lucy can answer, I remember and I open my mouth, trying to head her off, but it’s too late.

‘Isa’s related to Oscar Wilde,’ she says proudly to her husband. ‘Isn’t he your great-grandfather or something?’

‘Lucy,’ I manage, my throat tight with shame and my face hot, but Marc is already looking at me quizzically, and I know what he’s thinking. Oscar Wilde’s children all changed their name after the trial. He had no great-granddaughters – let alone any called Wilde. As I know perfectly well. There is only one thing for it. I have to confess.

‘Lucy, I’m so sorry.’ I put down my fork. ‘I … it was a joke. I’m not related to Oscar Wilde.’

I want the ground to swallow me up. Why, why were we so vile? Didn’t we understand what we were doing, when we pitted ourselves against these nice, credulous, well-brought-up girls?

‘I’m sorry,’ I say again. I can’t meet Marc’s eyes, and I look past him to Lucy, knowing that my voice is pleading. ‘It was … I don’t know why we said those things.’