If you’re Jan Morris it must get boring being asked about your sex change operation all the time; being questioned endlessly about the what and the how and the why and the was-it-sore of it.

“Oh God, not that,” she says when I do bring the subject up halfway through our conversation on a mild afternoon in west London. “No I don’t want to talk about this. I wouldn’t have had this if I knew we were going to stray into these territories. Forgive me, it was so long ago.”

It was 1972, to be exact, in Casablanca, when James Morris, former soldier, former journalist and full-time writer became Jan. She’s lived half a life since then, got divorced (though she never actually separated from her partner Elizabeth), continued to raise ­children who now have children of their own, regularly went travelling and then wrote about those travels, resulting in hugely acclaimed books (some 40 in total now), the latest of which, Contact! is the ostensible reason for our conversation.

And for that half a life, and much of the life before it too, she would argue, what happened in Casablanca isn’t that relevant. It’s old news, she says today. Part of the story, but not the main part. “Yes, that’s exactly it,” she says when I suggest as much. Which is, I guess, why she gets fed up being asked about it. “Absolutely.”

Still, you want to know, don’t you? You want to ask. “I haven’t changed, I can tell you that,” she does tell me when I do. “I’m exactly the same person as I was before. What has changed, of course, is other people’s attitudes to me and that makes my attitude to them different. But me at the centre of it is unchanged, I assure you.”

Unlike my line of questioning, age has not yet wearied Morris. The travel writer is 83 years old yet still stands straight up, touching the high side of 6ft in her flat shoes, her unruly mop of silvery gray hair adding possibly a couple of extra inches to her height. Her face has escaped any excessive, Audenesque imprint of the passing of the years. Her outlook too is unbowed. This afternoon she is by turns spiky, sullen, inquisitive, and ­outspoken depending on the topic in hand. She’s also prone to bark out woofs of laughter and will tell the photographer she wants to see herself smiling in the pictures.

We are sitting in a rather overheated function suite in the basement of Morris’s favourite London hotel, spooning up the froth from our cappuccinos (well, I am anyway) as I try to discover who the “me at the centre of” Morris actually is. It’s not necessarily an easy task. Pose a question she doesn’t want to answer and she’ll happily inform you she’s not going to answer it. Tell me about your parents, I ask her at one point. “No, I don’t talk about my parents.” Why not? “Because I don’t want to.”

This isn’t rudeness so much as a kind of brusque self-containment, I think; the kind of brusque self-containment that in the end is not much interested in making it easy for nosey journalists who keep asking her about ... well, that’s where we came in, isn’t it?

Certainly, self-containment might help explain why it’s taken Morris the best part of 50 years and 40 books to write about the people she’s met on her many and varied journeys around the world rather than the places she’s been to. “If you read them,” she says of the many books that preceded Contact!, “there aren’t an awful lot of people in them really. I thought it was unfair in a way and misleading, so I scoured my memory and my books for glimpses of people I have met and ­remembered.”

Then again, it’s the writing about place that she’s revered for. “It’s a conceited thing to say,” Morris says before saying it, “I’ve always prided myself on getting the spirit of the city, not the spirit of the people in it. I hate being called a travel writer and I don’t believe I am a travel writer at all. I’ve never been the sort of writer who tries to get into the minds and souls and personae of the people I meet. For one thing, I’m no good at it. And for another thing, I don’t want to.”

Such an approach hasn’t hurt. Over the years she has garnered fans, a Booker nomination (for one of only two novels she’s written) and the title of 15th best writer in Britain since the war, courtesy of The Times newspaper (which admittedly is an honour you could consider as damning with faint praise, but still – it’s a lot better than being the 37th or the 293rd). “I’ve always loved the writing part,” she tells me. “It’s been a great, great pleasure to me.” And even in the rather slight confection that is Contact! this love is clear, as clear as it is in her more celebrated books on Venice or Oxford or her vivid, epic trilogy about the history of the British empire, Pax Britannica.

She defines herself through books. Ask her what home means and she says, “Do you want me to be honest? I suppose it means books.” They fill every corner of her home in rural north Wales. Ask her about childhood and she starts talking about reading Huckleberry Finn. “I’ve loved it ever since.” That’s a travel book in its own way, I suggest. Twain’s book is after all an account of Huck’s trip down the Mississippi with his companion Jim, a runaway slave. “Well it is, isn’t it? That’s right.”

Morris would have read it in rural Somerset, where she spent her childhood (or “his” childhood as it would have been at the time). She won’t talk about her parents but she will say that the life she led then in the late 1920s and early 1930s was “lovely”. That’s the important thing, she says. “Spoilt. Two elder brothers. I was the youngest, so it was easy.”

It was the army rather than literature that gave James Morris the travel bug. At 19 he was posted to Italy and Palestine as the Second World War drew to a close. “Suddenly being launched into truly exotic places had a great effect on me.”

Describe the 19-year-old boy she once was. “Pretty innocent. I really was. And I was already me. The first thing I can remember writing was a piece about Trieste. When I first got to Trieste I loved it from the start, but I was chiefly struck by its melancholy and by the feeling that it had been something great and wasn’t and by the feeling it was on the edge. It was in the fold of the map. It wasn’t one thing or the other. It was a mix-up of things. And I immediately liked that. And those are the places I like to this very day.” She reckons her 2001 book Trieste: The Meaning Of Nowhere is her best one.

Before his military service, James Morris had spent a short time as a journalist – a job he’d later return to – in the Western Daily Press in Bristol. “I went there for a few months and did what cub reporters did, reported inquests and police courts. It was very interesting because it was the middle of the war and Bristol was the place where many of the Atlantic convoys came in with Hollywood stars to entertain the American troops who were just coming into Britain. And I was usually detailed to these characters and it was very interesting. They had just come straight out of America into this horribly blitzed city which was dismal – everything falling around, burst pipes ­everywhere. And these characters used to come over in a state of shock when they found that they had to spend a few days there. But they were terribly nice and terribly pro-British.”

The first American Morris ever met was Irving Berlin, composer of White Christmas, Easter Parade and God Bless America. “That was something, wasn’t it. I should think I’m the only person alive who can claim the first American they met was Irving Berlin.”

She could indulge in a lot of such casual oneup(wo)manship if she chose. As a journalist Morris covered the ascent of Everest by Edmund Hillary and Sherpa Tenzing for The Times. It made her name. And yet she’s rather dismissive of the achievement she reported on. “Even then it was so remote from real life,” she says. “The idea that climbing a mountain is a very big deal – even the highest mountain of all – it isn’t all that big a deal, is it, really? They climbed a mountain. Well done them. But I very much liked the people who did it.”

She doesn’t sound like the ideal candidate for the job, does she? But then there wasn’t much competition. “The average age of The Times journalists was pretty high and I was very fit and obviously ambitious. I was the right person, I suppose. I don’t know how it went down with my colleagues. Some of them were probably jealous. Some of them were thankful they didn’t have to go.”

There’s that sense of self-absorption again. It keeps cropping up. And Morris is aware of it. “I’m always thinking of myself. I have no claim to unselfishness at all.” Ask her about her greatest achievement and she talks about her books, rather than her children or her partner Elizabeth. “Well, don’t tell her. That seems just part of nature. It doesn’t seem an achievement of mine. But the book is something that has come out of me.”

She met Elizabeth when he was studying Arabic at the School Of Oriental And African Studies in London. “We were in the same lodging house, not far from here. We ­immediately liked each other. Very lucky for me, wasn’t it?” Elizabeth, she says, is very sensible. “She’s obviously loyal. She has the capacity to love. What more can you ask of anybody?”

Well indeed, and it must have been a very deep capacity. How else do you deal with the news that, at the age of 46, having fathered five children (one of whom, tragically died very young), your husband has decided on a sex change operation. Their story, Morris admits, had its torments. Which is one way of putting it. Was she (or as it were at the time, he) unhappy before the operation, I ask, chancing my arm. “Well, one half of me was, yes of course. Otherwise I wouldn’t have gone through with it. It was a risky thing to do then, not least in Casablanca.”

But she feels she had advantages that others in her situation had not. “I had the advantages of Elizabeth, of course, and my family and also my trade which I was passionately interested in. I can see having to work in a bank as a bank cashier with an unhappy marriage it would be a very different matter.”

After the operation the couple were obliged to get a divorce. But they stayed together. What has kept them together? “Oh we just love each other. And we’re fond of each other. That’s the thing. You can love someone and not like them much.”

Last year, they went through a civil ceremony near their home in north Wales. It was all rather comical, she says. Tea and biscuits and a non-conformist minister Morris had met in Patagonia.

Why did they want to go through with it? “I liked the symbolism of it. She [Elizabeth] said it didn’t matter anyway – we’re exactly the same as we were before. It sort of rounded it off nicely. You’d be amazed how many people I’d never heard of who wrote to me to say how nice it was to have a story with a happy ending. And it was a happy ending, wasn’t it?”

Even at 83 Jan Morris has no desire to give up travelling. In fact, she’s not long back from Belgrade, she tells me. “I’ve not been there before. It was the only European capital I hadn’t been to. And do you know, I enjoyed it. It’s got a terrible reputation, the blackest of all. Yet I found myself liking it. Behind all the terrible stories – Srebrenica, all the villains who frequented it, all the terrible things the Serbians have done – I found it a very genial city.” Well, she adds, the people are genial. “It isn’t a genial city to look at. It’s rather an awful city to look at, I suppose. But, nevertheless, I enjoyed it. They were kind to me.”

Why does she keep leaving, I wonder. Hasn’t she got to a point where she’s travelled enough? She seems mildly astonished by the question. “I’ve never been asked that before. What would the attraction be to you?” There wouldn’t be one, I say. I’m a homebird. “It’s a kind of drug really,” she says. She worries about the time when she can no longer travel. She dreads not being able to drive her car. “The moment I can’t will be crippling. I’m not looking forward to that.”

Still, she appears in good health now. A few years ago she went through brain surgery, not once but twice. “It was trepanning like the Incas did, which is rather romantic.” She doesn’t sound like someone overly marked by this brush with mortality. “I dunno, there’s something very superficial about me, you know. There really is. I thought it would be all right.”

If she worries about anything, it’s about posterity. “It’s childish again. I’d hate to think that when I died all my books would be forgotten and me too. But that’s one of the great advantages of a writer’s life. You at least have the chance of leaving behind something that people are going to read.

“It shows how childish I am really that at home I’ve got all my books not only in the English editions, but all the editions – all the funny ones. Korean reprints, stuff like that. I’ve got them all. And I often walk up and down and gloat over them.”

Home for Morris means Wales and Welshness perhaps as much as it does books. She has a huge romantic attachment to the idea of Wales and a political attachment to the notion of European federalism.

As for England, well, she despairs of England. “I can’t feel any pride in it any more. I used to feel great pride in it. I think there comes a time in nations when they really do pass the moment of being great and they end being great and that’s happened to this country in my opinion”. What exactly is she despairing of though? “Oh, I’d be accused of all sorts of awful things like racism – which doesn’t enter into it. But I did like the cohesion of it, when people would genuinely feel that they were members of a single community and a great community. I miss the sense of pride in the past which was so real when I was young. Those are the sort of things. And I think it’s decadent. That’s a dangerous phase, isn’t it. It sounds like Hitler.”

It does a little. What’s your definition of decadence then, Jan? “A lack of principles. A lack of discipline and also discipline among the generations. The people who are to blame for so many of the problems of this country now are not the unfortunate young people, but their parents who have sort of given up a bit the idea of managing their children, who think it’s the province of the state or the school or something and therefore don’t try to do it themselves. And it catches of course because one child infects another child.

“But none of these things are perhaps irreversible. We all feel this, don’t we? I’m just expressing the public view.”

For the first time today Morris sounds her age, or the cliche of someone of her age. And it’s a tad rich from someone who admits she was always going off and not really thinking about the family she was leaving behind to Elizabeth’s care. Didn’t that cause any difficulties? “No, it never became difficult. I hope that’s what she thought. It didn’t come difficult for me, but then I was entirely selfish. I’ve been egocentric. Egocentric all my life.”

In the end, perhaps that’s the key to Jan Morris. And that’s why it doesn’t really matter that she won’t talk about what happened to her in Casablanca. Because, whether man or woman, what she (and before that he) has always been – wilfully, brazenly in a way, gloriously so – is utterly herself.

Contact! by Jan Morris is published by Faber & Faber, priced £14.99.