Ever thine. Ever mine: How romantic are today's authors?

There's a memorable moment in the recent movie, Sex and the City, when Carrie lugs out an oversized book called Love Letters of Great Men, and entertains Mr Big with flowery passages from Byron and Bonaparte. It's a scene that had SATC fans rushing out to bookshops, only to discover that while the letters quoted were real, the book was never more than a Hollywood prop.

It didn't take long for publishers to plug the gap. Earlier this month, a week ahead of schedule, British publisher Macmillan released Love Letters of Great Men, a book that promises "some of the most romantic letters ever written." Dominated by the greats - Pope, Flaubert, Browning, Burns and Keats – it opens with Pliny and closes with letters from the Great War. It features letters from the movie, including Beethoven's unsent missive to his Immortal Beloved ("Ever thine. Ever mine. Ever ours") and Napoleon's promise to shower Josephine with "a million burning kisses as under the Equator." Chosen with an eye to copyright, readers looking for examples of more contemporary tendresse - Dodi to Diana, Sarkozy to Carla - might have to look elsewhere.

The author's editor, Ursula Doyle, a former publisher at Picador, says that the entries were "self-selecting" and chosen for their narrative interest and what they revealed about the correspondents' relationships. Preferring the more domestic entries to the "great outpourings of devotion", she directs us to Charles's Darwin's plea for "a nice soft wife on a sofa with good fire..." and Daniel Webster's circumspect flirtation with a much younger woman, largely addressed to her mislaid bonnet.

While the Sarah Jessica Parker Effect may have triggered a new hunger for historical billet doux, an appetite for other people's letters has always been with us. Medieval monks did their best to keep Abelard and Heloise's sweet-nothings in circulation, while classics masters have always run a quiet trade in the love letters of Marcus Aurelius. The last popular anthology to fly off the shelves was Antonia Fraser's best selling Love Letters. Complied in 1976 at the height of her affair with Harold Pinter, it sold in its thousands. "It is obvious that I am on the side of love letters," she wrote in her somewhat brazen introduction. "Anyone can write a love letter and almost everyone has."

Or have they? Anyone over 40 may have a secret cache of letters packed away in a biscuit tin under the bed, but lovers in the digital age are more likely to have assigned their erotic reminiscences to a memory stick. If letters have been killed off by off text and email, then love letters are the first casualties. Perhaps, like Carrie, despite enjoying the undeniable pleasures of instant messaging, what we all secretly crave is the perfumed note slipped under the door, or as Victor Hugo liked to call it, "a kiss in the post."

Whatever the improvements in computer print outs, the talismanic power of a handwritten letter is hard to beat. Mavis Cheek, a novelist whose latest novel, Amenable Women, required an in-depth study of the love letters of Henry VIII, has handled some the classics in the canon, including her own. "You can carry them around, squirreled away on your person, and bring them out occasionally and sigh – or gloat. With one love affair of mine that ended I demanded back all my letters. They were too good to leave behind. He resisted, I insisted. And got them."

As we know from any amount of fiction, there has always been something dangerous about love letters and their ability to fall into the wrong hands. Slapping "Private and Confidential" all over a hand written letter can be the equivalent of clicking "Forward to All". Several years after leaving a box of old letters at her parents' house, novelist Kate Long recalls getting a call from her dad commenting on their "fruity" content.

Some belletrists, of course, write only with their public in mind. Ursula Doyle gamely admits that her anthology might have been better named "Great Men: Going On About Themselves Since AD 61." Certainly, she says, some of them would have "benefited from being taken aside and gently told: it's not All About You". The critic and novelist Amanda Craig agrees: "The problem with Great Men is that they do everything, including making love and writing love letters, looking over their shoulder at Posterity."

While the extravagant prose of the 18th century might owe more to convention than passion, it is also refreshingly free of performance anxiety. A recent anthology of fictional love letters, Four Letter Word, featuring contributions from some our best known contemporary novelists, shows just how far high romance has fallen out of favour. According to one of the book's editors, Rosalind Porter, the men turned in either sarcastic or apologetic letters, while women "wrote angry ones." Says the novelist Daren King (who writes love notes on beer mats to his long-distance love): "Perhaps the term 'love letters' puts men off. It's not terribly masculine."

And that brings us back to the arch commitment phobe, Mr Big. Having left Carrie at the altar he must win her back. Does he hunt around for a pen that works, or whip out his Blackberry? His businesslike solution is to copy out vast chunks of Love Letters of Great Men and paste them into his email. Is he a cad who can't be bothered to come up with his own pillow talk, or a man who, recognising his creative limitations, deserves credit for typing out every single love letter in the English language? Either way - with a little help from the boys - he eventually gets the girl.

Words of love: Some leading writers share their own moments of passion

Meg Wolizer

My very first boyfriend, when I was 15, used to send love letters from his suburban home to mine, sometimes using calligraphy and sealing wax and occasionally referring to me as "Milady," and often burning the pages around the edges so the whole thing resembled the Declaration of Independence. But a love letter is a love letter, and I will always keep these, even though, if they were to be published, they would have to appear in an anthology called Love Letters from Boys with Enlarged Adam's Apples and Posters of Led Zeppelin on Their Walls.

Zoe Heller

There's a sexy bit in one of Flaubert's letters to Louise Colet that I like very much: he writes about her looking back on their lovemaking when she's old and how he wants her "dry bones" to quake. And I've always liked Captain Wentworth's letter to Anne at the end of Persuasion. Not so much the prose as for the fantasy of having an apparently indifferent man turn out to be gagging for you.

Andrew St George

Pierre Abelard's 12th-century Historia Calamitatum (The Story of My Misfortunes) is one of the greatest of all love letters: it made Heloise fall in love with him all over again, even though the letter was not intended for her, and despite the fact that by then he was a castrated monk; platonic love ensued, and a handful of epistles on the nature of love itself. I'd also include Shakespeare's sonnets, language at full stretch knowing it will last longer than any of the loves it envisages. The 18th century made a mockery of love letters lost or misdelivered – Fielding and Smollett made careers out of it. In the 19th century, Elizabeth Barrett had the time and means to languish on a sofa in Wimpole Street and trade hundreds of arcane love letters with Robert Browning, using the five or six daily deliveries in London in the 1840s: the result was a happy elopement to Italy. My favourite 20th-century love communications are the ones we never see, like the weekly "familygram", when our submariners receive 40-word long messages from family, leagues from home. These are greetings which cannot be returned, as this would reveal their submarine's position.

Michele Roberts

I receive lots of love letters from time to time. Currently I enjoy receiving late-night poetic text messages: so intense and compressed, as good poetry should be. I first bought a mobile phone five years ago so that a lover and I could communicate secretly. I saved all his text messages. I write love letters whenever I'm in love. I write love poems as love letters. I know when I'm in love because I start writing love letters or love poems to that person. Physical desire, for me, needs expression in poetry. I need a symbolic language (ie not a romantic or sentimental one) to express desire.

Mark McCrum

Do people really write love letters any more? People seem to have converted to texts and emails instead. I have sent love letters, but rarely during the affair. Most were afterwards trying to get back together with the girl. Bit of advice for men: you should send the letters before or during the affair, not after. I have sent a few saucy texts; and people do seem to send texts instead. It's taken over from love letters. Who sits down and writes love letters? Apart from long distance relationships no one really, and even then it's normally emails. One woman informed me on day two or three that she didn't like my texting style and warned me it might put our relationship at risk. She eventually banned me from texting and emailing. But this is all in the past as I'm happily married now.

Jenny Colgan

Love letters are great, but anything will do. Personally I think the most romantic lines ever written are: "Some day when I'm feeling old, and the world is cold, I will get a glow just thinking of you, and the way you look tonight." And it makes it even more romantic to think that it is sung somewhere every second of every day. I admire anyone who can bear to write dirty in love letters, I can't even do it in my novels, writing about people who don't even exist.

Salley Vickers

The best love letters are written by children. My favourite one reads: "Dear Sal, I love you very much but next time, please buy me a train."

Kate Long

My best love letter was one where I thought the relationship was over, and then I got a letter from him saying, "Let's try again." He had drawn a picture of two dogs sitting contentedly in front of the fire. I cried my eyes out over it. The week before I got married, I re-read all my old love letters; I had a fair few because I'd been away to university, and spent months every year apart from the boys I was dating. Then I put all of them except a tiny bundle into a heap on my parents' lawn, and burned them. It felt as though, by doing that, I was making a commitment to my husband-to-be that I wouldn't "look elsewhere".