Danny Baciagalupo, the protagonist in your new novel, is a writer. You've written about writers before, haven't you?
No. I had made characters writers in my novels before. But I'd never given a writer what is so inseparably my process as a writer as I did in the case of Danny. So I think it's totally fair to say that everything I say about him and the writing is modelled as faithfully as I could make it on my experience. Perhaps more deeply or tellingly autobiographical are not the things in the book that have happened to me, but the things I hope never will, which obsessively recur and recur and recur.

And those are the anxieties that drive you?
Yes. What you wish for repeatedly shows up in a psychologically autobiographical way. What you dread and hope never happens shows up and is repeated in a psychologically autobiographical way. The fact that Danny went to the same school as me is a superficial detail. And in any case, I'm certainly more politically engaged.

How politically engaged are you?
I think that writers are, at best, outsiders to the society they inhabit. They have a kind of detachment, or try to have. Of my 12 novels, I would identify only two of them as unashamedly political - A Prayer for Owen Meany and The Cider House Rules.

You've described the writerly "process" in the past as laborious, a matter of continuous rewriting.
My only hesitation with the word "laborious" is that it sounds like something you don't enjoy. And I love the repetition of it, the work. There is little that can make Danny elated in the novel - there's not much reason for him to feel elation. But he's a writer, and at that moment when he realises that he's starting again, it feels like the greatest fun.

How do you start a novel?
With the last sentence. Every novel of mine began with a last sentence, and not even the punctuation in those 12 last sentences changed. The first couple of times that happened to me, I thought it was an oddity. I didn't recognise it as a habit, nor would I have labelled it a "process". But
then I came to recognise that this is the way my mind works.

So once you have that last sentence, it's a matter of filling in the rest of the novel?
When people ask me what my novels are "about", the word "about" gives me the chills. I believe that, in any novel of mine, the principal objective is the construction of the whole. The excitement for me is the architect's excitement. That little road map I make, making my way backwards to where I think the story should begin, that little sketch, the skeleton of the novel, the scaffolding of the building I've not yet made, is nothing but an outline of the action of the story. There are no details. The details emerge as the sentences do. I sometimes think that what I do as a writer is make a kind of colouring book, where all the lines are there and then you put in the colour. I never start writing the novel, consecutively telling the story, until I've gone from that last sentence to the first. I now have those two poles and I know all the action. From the moment I start writing, I don't have to think about what's going to happen, and maybe this is why Thomas Hardy is almost as important to me as Dickens. I like the writing in Dickens far better than I like the writing in Hardy, especially the dialogue. For someone like me, who knows the fate of all his characters, how wonderful it is that Hardy believed, as he surely did, in the predetermination of all his characters.

Any influences?
My first attraction to writing novels was the plot, that almost extinct animal. Those novels I read which made me want to be a novelist were long, always plotted, novels - not just Victorian novels, but also those of my New England ancestors: Herman Melville and Nathaniel Hawthorne. The New England 19th century was the part of American literature that was richest for me. I was never a Hemingway, Fitzgerald or Faulkner person - all too modern for me. I like the old stuff.

John Irving's "Last Night in Twisted River" is published by Bloomsbury (£20)