We all have to pay the price of love

His letters were long, sentimental and dull. You can see why the relationship didn't last

If Francis Bacon (the 16th-century essayist, not the 20th century painter) had seen the James Hewitt interview on that American chat show, would he, I wonder, have taken up his quill to write one of his famous dissertations on the nature of cads or the value of love letters? Both are fascinating subjects. The latter in time, however, would be more useful to social historians because while cads, like diamonds, are forever, love letters are fast approaching the end of their shelf life.

Incidentally, I hope I've got my facts right. I only caught a snatch of the Hewitt interview on a monitor in the transit lounge of Casablanca Airport, which had previously disclosed that Cilla Black was leaving Blind Date and Prince Charles is suffering from depression. I bet he is. The prospect of Blind Date without Cilla has cast a pall over the entire nation.

Only the other day I ran into a television producer who told me he was planning a special celebrity version of Blind Date featuring members of the Royal Family and their households. You've have Princess Michael, for instance, choosing a decorator to do up her free flat in Kensington Palace or Prince Edward deciding which footman he'd prefer to go pony-trekking with in the Brecon Beacons. I can just hear Cilla introducing Mrs Parker Bowles. "Eeh, you look gorgeous, just gorgeous, and I love those ear-rings."

During the course of her six-year love affair with Major James Hewitt, Princess Diana apparently wrote him 65 letters. Only 65? That's less than one a month, for heaven's sake. When Winston Churchill was courting the beautiful Clementine Hosier, he used to write her three letters before breakfast begging her to tell him when they could next meet. This was when she was staying at Blenheim as a house guest only a couple of staircases away from Winston's own room.

The parlour maid acted as postman. He called her his dearest Clemmy Cat, she referred to him as her most precious Pug Wug, and if you don't believe me there's a wonderful collection of their letters on cassette for £8.99.

James Hewitt, I understand, is hoping to get £4m for just 10 of the Princess's billets-doux, which works out at £400,000 per billet. I do hope that they're worth it. For that price I would expect something rather more than just doux – a few quotations from Ovid, in Latin, on the nature of passion, a lot of crushed rose petals between the pages, a sonnet possibly starting: "Shall I compare thee to a Gucci shoe? Thou art more supple, more invincible, Oh James I love you more than Jimmy Choo...'' And rows and rows of tear-smudged kisses under the signature.

I wonder what silly pet names they called each other. Was he her Chocolate Soldier, her Galloping Major, her Knave of Hearts, her Jimmy-Jammy Dodger, her Giant Peach – and was she his Princess of Wiles, his Sly Di, his Shy Di, his Do or Di? We'll have to wait and see.

What cheers me about this otherwise tacky saga of passion, betrayal, greed and monumental caddishness is the fact that Diana took the trouble to write to him instead of sending a text message saying "drst drlng I thnk u 4 a wndfl ev" followed by a row of pink hearts. When I have grandchildren I shall enjoy telling them what granny used to do with funny old-fashioned things called envelopes.

I love writing letters. Over the years I must have written hundreds, though significantly not a lot of love letters. Somewhere at the bottom of a cupboard I have a bundle of airmail letters, some still unopened, from my first fiancé who wrote to me every day throughout the year I went to work in Tehran.

Iranian post then was as erratic as the Royal Mail now. Sometimes I'd get nothing for weeks, then 17 letters at once. Reading them wasn't much fun. They were invariably long, sentimental and dull, touching, as they always did, on absence, heartbreak and the melancholy music of time. You can see why the relationship did not last.

From my husband I have had a single love letter. It was written in response to the passionate missive I left in his bedsit one morning. It reads thus: "Dear Sue, I love you, too. The iron is in the cupboard behind the bicycle. Yours Ian." If anyone wants it for £400,000, or even £40, I'll take a cheque. I'm not a cad, I'm a realist – and anyway, I know it by heart.