I’m fine now, absolutely fine. Apart from the heights issue, obviously, which I will deal with, when I have time.

‘You should really go and see someone about your phobia,’ Dan says, reading my thoughts in that spooky way he has. ‘PS?’ he adds, when I don’t answer at once. ‘Did you hear me?’

‘PS’ is Dan’s occasional nickname for me. It stands for ‘Princess Sylvie’.

Dan’s whole riff is that when we met, I was the princess and he was the poor working guy. He called me ‘Princess Sylvie’ in his wedding speech and my father chimed in, ‘I guess that makes me the King!’ and everyone cheered, and Dan did a charming mock-bow to Daddy. The truth is, Daddy looked like a king, he was so distinguished and handsome. I can remember him now, his golden-grey hair burnished under the lights, his morning coat immaculate. Daddy was altogether the best-dressed man I’ve ever known. Then Daddy said to Dan, ‘Carry on, Prince Daniel!’ and twinkled in that charming way he had. And later on, the best man made a joke about this being a ‘royal wedding’. It was all really funny.

But as time has gone on – maybe because I’m a bit older now – I’ve got tired of being called ‘Princess Sylvie’. It rubs me up the wrong way; makes me flinch. I’m wary of saying anything to Dan though, because I have to be tactful. There’s a bit of history. A bit of awkwardness.

No, not ‘awkwardness’. That sounds too extreme. It’s just … Oh God. How do I put this, without …?

OK. Another key fact about me: I was brought up in a fairly privileged way. Not spoiled, definitely not spoiled, but … treated. I was Daddy’s girl. We had money. Daddy originally worked in the airline industry as an executive, then received some huge windfall of shares when his airline was taken over, and started his own consultancy. And it did brilliantly. Of course it did. Daddy had the kind of magnetic personality that attracted people and success. If he was travelling first class with a celebrity, by the end of that flight he’d have that celebrity’s card and an invitation to have drinks.

So we didn’t just have money, we had perks. Expensive flights. Special treatment. I have so many photos of me as a child, in the cockpit of some plane or other, wearing the captain’s hat. In my early childhood we owned a house in Los Bosques Antiguos, that gated development in Spain where famous golfers get married in Hello! We even hung out with a few of them. We had that kind of life.

Whereas Dan … didn’t. Dan’s family are lovely, really lovely, but they’re a sensible, modest family. Dan’s father was an accountant and he’s very big on saving. Very big. He started saving for his house deposit when he was eighteen. It took him twelve hard years, but he did it. (He told me that story the very first time I met him, and then asked if I had a pension.) He would never whisk the whole family off to Barbados on a whim, like my father did once, or go shopping at Harrods.

And don’t get me wrong: I don’t want trips to Barbados or shopping trips to Harrods. I’ve told Dan that a million times. But still, Dan is a bit … what’s the word? Prickly. That’s it. He’s prickly about my background.

What’s frustrating is that he wasn’t like that when we first got together. He and Daddy really got on. We’d go out sailing, all four of us, and have a great time. I mean, Daddy was obviously far better at sailing than Dan, who’d never done it before, but it was OK, because they respected each other. Daddy would joke that he could do with Dan’s eagle eye overlooking his accounts team – and he did genuinely ask Dan’s advice a few times. We were all relaxed and easy.

But somehow Dan got pricklier as time went on. He stopped wanting to go sailing. (To be fair, it was harder once we had the girls.) Then three years ago we bought our house – using an inheritance from my granny as a deposit – and Daddy offered us a top-up but Dan wouldn’t take it. He suddenly got all weird and said we’d relied on my family quite enough. (It didn’t help that Dan’s dad arrived to see the house and said, ‘So this is what family wealth buys you,’ as though we were living in a palace, not a three-bedroomed house in Wandsworth on a mortgage.)

After Daddy died, everything was left to my mother and she offered us money again – but Dan wouldn’t touch that, either. He was even more prickly. We had a bit of a row, in fact.

I can understand that Dan is proud. (Sort of. Actually, I don’t relate to it at all, but maybe it’s a male thing.) What I do find hard, though, is the way he’s so defensive about my father. I could see their relationship becoming strained, even when Daddy was alive. Dan always said I was imagining things – but I wasn’t. I just don’t know what happened or why Dan got so tentery. (That’s when I invented the word.) It was like he began to resent Daddy, or something.

And even now, it’s as if Dan still feels threatened. He’ll never sit down and reminisce about my father – not properly. I’ll sit down and start scrolling through photos, but Dan won’t focus. After a while he always makes an excuse and moves away. And I feel a little ache in my heart, because if I can’t reminisce about my father with Dan, who can I? I mean, Mummy … She’s Mummy. Adorable, but you can’t actually have a conversation with her or anything. And I don’t have any siblings.

Being an only child used to bother me. When I was a child I pestered and pestered Mummy for a baby sister. (‘No, darling,’ she would say, very sweetly.) Then I even invented an imaginary friend. She was called Lynn and she had a dark fringe and long eyelashes and smelled of peppermints and I used to talk to her in secret. But it wasn’t the same.

When Tessa and Anna were born, I watched them, lying face to face, already locked into a relationship no one else could penetrate, and I felt this huge, visceral pang of envy. For all that I had as a child, I didn’t have that.

Anyway. Enough. I’ve long got over being an only child; I’ve long grown out of my imaginary friend. And as for Dan and my father … Well. I’ve just accepted that every relationship has some little fault line or other and this is ours. The best thing is just to avoid the topic altogether and smile when Dan calls me ‘PS’ because what does it actually matter?

‘Yes,’ I say, coming to. ‘I’ll go and see someone. Good idea.’

‘And we’ll decline this.’ Dan taps the Sky Garden invitation.

‘I’ll write to David Whittall,’ I say. ‘He’ll understand.’

And then Tessa spills her milk, and Anna says she’s lost her hairclip and she only wants that hairclip, because it has a flower on it, and the morning routine takes over.

Dan’s changed his job since we first met. Back then, he worked in a huge property-investment company. It was lucrative but fairly soul-destroying, so he put money aside every year (like father, like son) and finally had enough to start his own company. They make self-contained, pre-fabricated, sustainable office units. His office is on the river in east London and he often drives the girls to school, because it’s on his way.

As I’m waving goodbye from the front doorstep, I see our next-door neighbour, Professor Russell, picking up the paper. He has a comical tuft of white hair that makes me smile every time I see him, although as he turns, I quickly put on a straight, grown-up face.

Professor Russell moved in earlier this year. He’s in his seventies, I’d guess. He’s retired from Oxford University, where he taught botany and apparently he’s the world expert on some kind of fern. Certainly, his garden is full of a massive new greenhouse and I often see him in it, pottering among the green fronds. He lives with another white-haired man who was just introduced as Owen, and I guess they’re a couple but I’m not totally sure.

I’m actually a bit wary of them, because pretty much the first thing that happened after they moved in was that Tessa kicked a football over the fence and it landed on the roof of the greenhouse. Dan had to get it, and he cracked a pane of glass as he was climbing up. We paid for it to be replaced, but it wasn’t the best start. Now I’m just waiting for them to complain about the girls’ screaming. Although maybe they’re a bit deaf. I hope so.

No, scratch that. I don’t hope they’re deaf. Obviously not. I just … It would be convenient.

‘Hello!’ I say brightly.

‘Hello.’ Professor Russell gives me a pleasant smile, although his eyes look abstracted and distant.

‘How are you enjoying Canville Road?’

‘Oh, very much, very much.’ He nods. ‘Very much.’

His gaze has already slid away again. Maybe he’s bored. Or maybe his mind isn’t what it was. I can’t honestly tell.

‘It must be strange though, after Oxford?’ I have a vision of Professor Russell wandering through an ancient quad, wearing a sweeping black gown, lecturing a bunch of undergraduates. To tell the truth, that vision suits him more than this: standing on his front doorstep in a little street in Wandsworth, looking like he’s forgotten what day it is.

‘Yes.’ He seems to consider this as though for the first time. ‘Yes, a little strange. But better. One has to move on.’ His eyes suddenly fix on me, and I can see the wink of sharpness in them. ‘So many of those fellows stay on too long. If you don’t move on in life, you atrophy. Vincit qui se vincit.’ He pauses as though to let the words breathe. ‘As I’m sure you’re aware.’

OK, so his mind has definitely not gone.

‘Absolutely!’ I nod. ‘Vincit … er …’ I realize too late that attempting to repeat it was a mistake. ‘Definitely,’ I amend.

I’m wondering what vincit-whatsit means and whether I could quickly google it, when another voice hits the air.