Dame Muriel Spark: The brightest of sparks (and still in her prime)

I meet Dame Muriel Spark – "Britain's greatest living novelist" – at a hotel in Italy, in Arezzo, which is about an hour out of Florence. Britain's greatest living novelist? What do you think, Mrs Spark (I would never dare call her Muriel), when people refer to you as that? "It makes me wonder", she says, "what they've been reading. Now, I hope you'll take that with a pinch of salt!"

She arrives with her assistant of 32 years, the painter and sculptor Penelope Jardine, who is 14 years her junior and with whom she shares a house about a 40-minute drive away. She walks awkwardly, with a stick. Arthritis. Hip operations. "I've now got a nurse coming in twice a day." Her eyesight is fading. "It's awfully bad... glaucoma... although I have drops to contain it." Still, she is not diminished. Still, she is abundantly alive. And her reddish hair colour is, she declares hotly, very much her own. "I know people don't believe me when I say I don't dye it, but I don't. I don't colour it, even though I'm 83. I don't dye it, do I, Pen?"

"No,"confirms Penelope.

Perhaps, I suggest to Penelope, Mrs Spark dyes it once you've gone to bed. Out she creeps, into the bathroom, with her bottle of Miss Clairol or L'Oréal Excellence, because she's worth it. Perhaps, I conclude plainly, Mrs Spark dyes it on the quiet.

"That would explain," suggests Penelope, "those strange chemical smells... the colour on the towels... "

"Exactly," I say.

Dame Muriel Spark does not mind being teased. She giggles. She has sweet little pearly-white teeth. I do not know if they are her own or not. I do not know if Penelope knows if they are her own or not. After all, she could be putting them in before Penelope gets up.

She says she wishes we could have met at the house. But, she sighs, she and Penelope have people staying. Does the sigh, I ask, mean they are staying rather too long? "Yes," she says. "Much too long." Plus, she adds, a lawyer is visiting later this afternoon to deal with various insurance claims. First, last year, the house was struck by lightning. "The bell tower fell into my bedroom. Frightful mess everywhere." Then, "a big burglary followed it, because the scaffolding was nicely up around the house." The burglars made off with jewellery, paintings, bronzes and the refrigerator. The refrigerator? "The refrigerator, yes. It was an absolutely new refrigerator. The old one got bust by lightning. We think it was an inside job." Dame Muriel does seems prone to mishap. Once, in Florence, she had her bag stolen from the back of her chair in a restaurant. "It had an unfinished poem about a hat in it. When I went to the police, they asked me what was in the bag, and I said, 'There's a poem.' The policeman asked if I could describe the poem. I said it was about a hat. I didn't get the feeling he took it seriously at all... "

I admire the handbag she has brought along with her today. It's a loud, patchwork leather affair, made up of lots of multicoloured squares in pink, green, violet, turquoise, red. "Isn't it fun?" she agrees. "I bought it from a little boutique that gets them from Florence. Oh, I do wish I could give it to you, but I've nothing else to put my things in." I admire her high-ly diamond-splattered gold ring, too. "A mad moment in Cartier," she says. "What happened was, Penelope went in and said: 'Can you mend this watch?' And they said: 'Sorry, madam, we only do Cartier.' In the meantime, I was in the other side of the shop, having a look to see what I get could get, and, in the end, Penelope got a new watch and I got this ring." She is not, she says, too extravagant with money. "I never spend more than I earn." She is not like her mother, Sarah, an Edinburgh piano teacher, "who spent money as soon as she got it. She would always buy a hat suitable for a garden party, and, of course, in Scotland, you know... " Not many garden parties? "No. Everyone else wore tweed hats." Muriel's greatest extravagance has been her car, an Alfa Romeo, which she bought with the proceeds of yet another literary prize. "It's a very good make. And a very good number all round, isn't it, Pen?"

Frankly, and for what it's worth, which probably isn't very much, I had not expected Dame Muriel Spark to be like this. What had I expected? Someone rather glacial, I suppose, whose super-sharp, vastly superior intellect would cut cleanly down through mine, like a wire through cheese. I had not expected this warmth, this friendliness, this almost girlish complicity. "I like being interviewed, don't I, Pen?" she says. "You must come and stay with us on a non-professional basis," she says. "Here, have my Cartier ring, and take the car," she doesn't say, more's the pity. I think, though, she would give me her handbag, if only she could find something else to put her things in. (Damn! Why didn't I think to hang on to my Duty Free carrier?) I suppose I could wrestle her to the ground for the ring and the Alfa keys, but would that be seemly? Her being 83 and on sticks and a Dame of the British Empire and all.

Anyway, I've probably read all her books over the years. From the early ones – Memento Mori, A Far Cry from Kensington, The Girls of Slender Means, The Prime of Miss Jean Brodie – right though to the latest, a complete collection of her short stories and the novel, Aiding and Abetting, which is a typically sly, darkly comic take on the Lord Lucan business. Mostly, they are rather heartless affairs, spilling with heartless people doing heartless things, recounted in an authorial voice of almost forensic detachment. Warmth. Tenderness. They just don't figure. Are you ever sentimental, Dame Muriel? Do you ever cry, for example? "In life?" In life, yes. "I wouldn't cry for very much in life. I don't have many sentimental moments. I'm rather chary of them. I read so much fiction as a child, so much sentimental fiction, that I'm rather dry-eyed about it all. The same with movies. Or the sort of movies we used to go to. Everyone would be crying, and I wouldn't."

I don't think her warmth today is a sham, a ploy to get me on her side. After all, with her reputation, she doesn't need anyone on her side; least of all me, with my mind of cheese. But I suspect that if I did turn up on her doorstep to stay, she'd be fairly horrified. Another bore, she would think, who is going to take up my time. Nothing, you see, must get in the way of Muriel Spark and her writing. And nothing ever has. When her first novel, The Comforters, turned her into something of a celebrity here, she fled to New York. When the successful Broadway version of Jean Brodie brought her further celebrity, she fled to Italy. Does she miss England? "I do miss the language. I liked being on top of a bus, listening to people." I say that, when it comes to eavesdropping, what I miss most is the days of crossed telephone lines. "Oh yes!" she agrees. "Weren't they wonderful? And sometimes you would say something quite frightful!"

Has love ever been allowed to distract her? Did you ever fall in love easily, Dame Muriel? "No, I didn't. I was much too interested in my work. I felt more like a poet than a prose writer, and I could never have loved a man who would permanently put me off my writing. Never." Could you have loved a man who put himself second to your writing? "I'm not sure about that. It's a bit too theoretical. He'd have had to be awfully attractive." Of course, there's been speculation about Penelope and Dame Muriel. A journalist once even referred to Penelope as "big-boned", which Dame Muriel found most amusing. "Were they trying to say we are lesbians?" They are not, I'm convinced. They are companions, with, perhaps, Penelope intuitively knowing when to appear and when to withdraw. Plus, she does quite a lot for Dame Muriel. It's Penelope who drives her around in the Alfa. It's Penelope who cooks ("I like a nice, light soufflé," says Dame Muriel), cleans, makes the beds. Dame Muriel is not very domestic. "The last time I tried to make a bed, I broke two ribs, didn't I, Pen?"

In your younger days, were there a lot of affairs? No, she says. She was never a bit of a goer like her contemporaries Doris Lessing and Iris Murdoch. "I didn't have time. And I had to work especially hard as my parents got older. They'd been very good to me, had helped me with my son. My father got me my divorce when he could ill afford it. I had to work hard. I didn't have time for a fun life. I was busy writing, and people were grabbing my work." Divorce? Son? At 19, she married Sydney Oswald Spark, a schoolteacher 13 years her senior, with whom she emigrated to Rhodesia. She can't think why she married him now. Perhaps it was for the sex because, in those days, you had to be married to have sex. Whatever, he quickly revealed himself to be utterly mad, and was speedily dispatched to a "loony bin". The sex, though – was that good, at least? No, she says, it was not. Your wedding night? "An awful mess. Awful. Such a botch-up." Once divorced, she returned to Britain, leaving their son, Robin, then six, in a Rhodesian boarding school. It was the war, after all, and children were not allowed to travel. Post-war, Robin went to live with her parents in Edinburgh while Muriel found work in London.

These days, Muriel and Robin are estranged after a very public spat. He, an Orthodox Jew, claimed his grandparents (Muriel's parents) were both Jewish. Muriel said her father was, but her mother wasn't. Robin produced their synagogue marriage certificate to prove that they were. Muriel then produced her grandparents' wedding certificate to show that they had married in church. Oh, dear. It's not that Muriel, a Roman Catholic convert, would mind being Jewish. It's just that the truth is the truth. I wonder, though, if she could put one of her books back – unwrite it, unconceive it – for the sake of better relations with her son, would she? "No! No! His relationship with me is as much up to him. Besides, he's now 63 and it's a two-way thing, I don't think anyone would expect you to wish a good work of art to be non-existent. That's not a friendship or relationship worth having. It would put too much of a strain on a civilized relationship, which is what you have to have, once you have passed the mother-son stage." Can you ever pass the mother-son stage? "As they get older, you can't be pottering around them all the time, can you?" The absence of maternal feeling seems total. What was it Graham Greene once said? That in the heart of every writer there is a sliver of glass? I think Dame Muriel Spark's sliver may be a good-sized one.

I wonder about the process of novel writing. Does the confidence to set an imagined world in motion give someone the ability to write? Or is it the other way round? The other way round, she thinks. And you've always had the ability? "Oh, yes. It's inborn. Sometimes I've struggled for the peace of mind to write, but I have never struggled to write. It is still the easiest thing I do." Are there writers you admire or are jealous of, even? "I remember reading The Loved One by Evelyn Waugh and thinking: I wish I'd written that. Now, who else do I envy...?" Anyone contemporary? Nope, she can't think of anyone, although, "maybe I should... maybe that's complacent... now, we'd better go, hadn't we, Pen?"

Yes, she has to get back to the guests outstaying their welcome, and the lawyer. I watch her hobble off, with the gorgeous bag that could so easily have been mine (drat, drat and double drat!) "Remember," she calls over her shoulder, "that you must come and stay with us on a non-professional basis." She doesn't add: "Now, I hope you take that with a pinch of salt." Although I suspect she might have wanted to.

'Aiding and Abetting' is published by Penguin at £6.99. 'The Complete Short Stories' is published by Viking at £20