Simon Schama, once described as the artistic flipside of Stephen Hawking, is flustered. A marvellous book, I had said of Rembrandt's Eyes, his extraordinarily ambitious take on the great man, which is published this week and tips the scales at five and a half pounds. Not, I supposed, that he needed my praise. Schama's long line of iconoclastic cultural histories may have dismayed the greybeards of academe, but they have sold in their hundreds of thousands. On the contrary, he said, boyish smile glinting behind matter-of-fact glasses, he needed to hear it. This was a time of great tension when there was nothing to be done except wait for reviews and look through the text for flops, the technical term for pictures printed the wrong way round. Yes, I said, I had spotted one myself.
The smile froze, the eyes flashed. What? Where? Was I sure? He'd found two at proof stage but he didn't "sign off" on the final proof. He'd been over here, in England. Well, I admitted, it was actually my sharp-eyed daughter who had noticed. And now his mind is anywhere but in this coffee shop talking to The Irish Times. It's as if I can hear the cogs whirring, wondering which painting it might be. He needs to know. I call my daughter. Not there. Perhaps she has made a mistake, I say.
Simon Schama was born in Essex in 1945 - the night Dresden was bombed. Now he lives in the US, where he is Old Dominion Professor of Humanities at Columbia University in New York, though for the past six months he has been on leave of absence making a programme about the history of the British Islands for the BBC, which he stresses, will not be about "just England and the others but a history of the relationship between the nations". He has just been filming in Nendrum, a sixth-century monastery north of Belfast, which he describes as "incredibly beautiful. A deeply, poetically engaging place, really".
As a telly presenter he'll do well. No patrician condescension in the Kenneth Clark vein; nor the intellectual eggheadedness of Bronowski, both historians whose names live on in the annals of great television. Nor need we fear any Paxmanlike elitism.
One senses this man feels no need to sharpen his ego on our insecurities; he's as comfortable with his intellect as an eagle is with his sight. Nothing that special about it, it's just how he is. He communicates the most complex of issues with the fluency of flight.
Schama is the first to acknowledge that not everyone is enamoured of his populist approach. "There are certainly people who think that I have abandoned in some ways the more austere obligations of history; which are question-asking, analytical sifting and sorting and the negotiation between cause and effect. I'm completely unapologetic about the atmospherics, because that's what I love doing, the pleasure in living in the past and writing about it. But I always try not to have that happen at the expense of asking questions."
Brushing the dust off history and making it accessible to ordinary people is nothing new, he says. "I was taught by people in the early 1960s for whom the practice of style was not an optional add-on, it was a precondition of making it as a historian. You would never get away with some loose, dreary, obscure piece of academic writing, something that didn't sing in some way.
"These were people who came out of national service, who came to university to do their graduate work late. They needed to make a living through journalism, they were totally unapologetic about it - people like Alan Taylor and Denis Brogan. All these people saw it as part of your job actually to reach beyond the academy and didn't see it as a compromise to your scholarship within the academy. These two things were supposed to be held absolutely in balance."
SCHAMA still sounds entirely English. Just the odd "I guess" bears witness to his 20-year sojourn in America. However, there is no question of moving back. His children, 14 and 16, are firmly entrenched in the American education system, of which, in spite of its imperfections, he generally approves ("four years at university, instead of three, 13-week terms instead of 8").
Then there is his wife, Ginny, whom he met in Oxford when they were both doing their PhDs. She is "deeply American, a cattle rancher's daughter, born and raised in the Sierra Nevada". More to the point, she is a geneticist. "I am portable - I would love to be here for longer than six months, but I'm not going to get my wife to demolish her lab. You can't move a scientist just like that, like writers - years of experiments, equipment, grants and all the rest. It's impossible."
He even vacated his tenure at Harvard - the best history job on the planet, I'm reliably informed - when his wife was offered a job she absolutely couldn't possibly refuse at Columbia and he went with her, though he laughs at the "new man" halo. "I would love to wallow in this heresy. But I wasn't being asked to go to Tallahassee, you know, I was being asked to go to New York. How much of a sacrifice was this?"
And Schama loves New York. "A lot of America stirs, moves, enrages, and yet is still an extraordinary place: the baseball grounds, the taxi drivers, the street talk, the hucksterism, the Jewishness of New York means a lot to me." Not, he says, that he's an observant Jew. "But in New York it's really unremarkable, it's simultaneously a major part of New York culture; but it's also unremarkable."
Although Simon Schama is part of Columbia's Art History department and has taught that subject since 1979, he knows that Rembrandt's Eyes will raise hackles. "There are some who say he has no business doing this. That's why it's such a shock to have a flop. It's not what you want to have. You don't want to be seen as somebody who is taking a holiday among paintings from his real profession. And I do think of it as my profession. I don't see the two as being walled off from each other in any way. I was very happy to do art criticism for the New Yorker for four or five years."
And he'd like to do more. In the meantime, he's only half-way through the BBC series, the first half of which will screen next year. As we leave he asks me to call as soon as I have spoken to my daughter. It turns out to be a detail of a sleeve printed the wrong way round. I doubt whether any normal person would notice, but as Schama knows all too well, the carpers will be out there sharpening their knives.
Rembrandt's Eyes will be reviewed by Brian Fallon next Saturday