‘That makes a “yuh” sound,’ I told him. ‘Like “yard”. See, I’ve put all the sounds of the letters beside them.’

He studied the list with a small frown of fixed concentration.

‘It’s not the world’s easiest language to learn,’ I said. ‘And Superman you might be, but I don’t think even you could become fluent in one plane flight.’

Rob glanced over, with the crinkles showing at the edges of his eyes. ‘You think I’m Superman?’

‘The point is,’ I said, ‘you don’t need to be able to understand Russian. I’ll be there to translate.’ I knew from the warmth of my cheeks I was blushing, but Rob had already turned back to his alphabet.

Shrugging, he said, ‘I like learning things.’

Watching him working to master the letters and sounds on that napkin, I felt once again that small tug at my ribcage, that small wash of tenderness, and just as quickly I shielded my feelings and thoughts. But I was glad he’d come.

I’d been privately dreading the challenge of doing this leg of the journey without him. I’d told myself it was because he was just so much better than I was at seeing the past, and without him I didn’t stand much of a chance of accomplishing anything useful. Assuming I even found Anna, the limits of my own skills meant that I most likely wouldn’t be able to tie her to Catherine the First and find tangible proof that would help Margaret Ross sell her firebird carving for what it was worth.

If I’d had a month in St Petersburg, maybe. But in just a handful of days, I could never have done it. With Rob, now … with Rob, it was possible.

That was the reason, I’d told myself firmly, why I was so glad he had come. Only that. Not because of the way that I felt when he smiled, or the fact that I felt more completely alive in his company than I had felt for a very long time.

And as for that traitorous inner voice trying to get my attention, to point out that this couldn’t possibly last, that like holiday romances it only worked in the moment and wouldn’t survive a return to the real world – I buried that little voice deep down inside, and ignored it.

The real world, I knew, would intrude soon enough. But for now, just for now, I was here on a plane next to Rob, with his elbow and mine touching warm on the armrest between us, and I didn’t want to think further ahead.

He had picked up my pen and was carefully copying ‘Poбepт’ – his name – on the alphabet napkin. ‘How’s that?’

‘Perfect. But it should really be this, if you want to be properly Russian.’ I borrowed the pen back and wrote down a second name under the first, and then watched as Rob worked it out, letter by letter.

He said, ‘Brianovich? What’s that?’

‘Your patronymic. Unless you’re on really close, intimate terms with people in Russia, you don’t use their first name alone, you use their first name and their patronymic. All you do for that is take their father’s first name, and then add the proper ending for a man or woman. You’re Robert Brianovich, for example, because you’re a man, but if we had the same father my patronymic would be Brianovna.’

‘What is it really?’ he asked.

‘Philipovna.’

He gave the brief nod that I knew meant he’d got it all sorted. ‘So if I had two kids,’ he said, ‘Jean and Jack, they’d be Jean Robertovna and Jack Robertovich.’

‘You’ve got it. ‘Except little Jean would be “Zhanna” or “Yana” in Russian, and Jack would be “Ivan”.’ I said it the proper way: ee-VAHN.

Rob smiled. ‘So what’s “Nicola”, then?’

‘Well, there isn’t a Russian equivalent, really. My parents, I think, really wanted to call me Natalya, but nobody wanted to upset my grandfather, so they picked something more English.’

‘Your granddad’s not so keen on Russian names?’ Rob asked.

‘My grandfather doesn’t like any reminders of Russia.’

‘I see.’ His smile turned briefly private. ‘He’s not ower fond of me, either.’

‘What makes you say that?’ I cast my mind back to this morning, when I had been leaving my grandfather’s house and he’d stood in the doorway and glared out at Rob, and I’d thought that the two of them might have been—‘Rob,’ I began, ‘did you … ?’

‘No.’ His tone held a hint of amusement. ‘But he did.’

That floored me. ‘He spoke to you? What did he say?’

‘I’m not sure. What does this mean?’ he asked, before speaking a short and succinct Russian phrase that made people in nearby seats turn their heads, scandalised.

Even the older woman on the aisle leant over and told me, in Russian, ‘You should not be teaching him such things.’

Rob leant back, all innocence, closing his eyes as I sent him a look.

‘Aye,’ he said, ‘I’ve a feeling your grandfather’s not ower fond of me.’

The drive in from the airport took us past the modern factories and industrial monstrosities and bleakly structured Stalinist apartment blocks and buildings that belonged more to the stoic past, when the city had been known as Leningrad, than to the brighter history of pre-Communist St Petersburg.

My mother had been born here, and my grandfather. He’d been a little boy when Hitler’s armies had come overland and cut off the supply lines of the city, and like everyone in Leningrad he’d starved and suffered through more than two years of that relentless siege, those endless bitter winters, while the people all around, including many of his family, sickened, died or disappeared.