Is that it, then? We are born, live for a while, then vanish, leaving behind no trace - except what remains in the fading and uncertain memories of our survivors - of the things that beguiled our time on Earth: love, friendship, pleasure, amusement? Harsh though it seems, the answer is, essentially: Yup, that's your lot. Unless, of course, you happen to be an assiduous and energetic letter writer, and have the good fortune to be fond of someone else with similar inclinations. In that case, if the friendship prospers, you will build over the years by slow accretion a kind of cairn of letters; a solid monument to the mutable and dangerously perishable entity that is friendship.

How lucky, then, both for themselves and now, with the publication of a volume of their letters, for a wider readership, that Patrick Leigh Fermor and Deborah Duchess of Devonshire, should have met, become friends and engaged in a correspondence that began in the mid-1950s and has endured for more than 50 years. “When this volume went to press,” a valedictory editorial note says, “the two correspondents, aged 88 and 93, were still keeping up a lively exchange of letters.”

Sir Patrick, born in 1915, and the Duchess, born in 1920, come from a generation where the principal means of communication with someone from whom you were apart was to write a letter. As technology advances, the Duchess occasionally urges a fax on Leigh Fermor as an efficient means of making arrangements. But you have the clear impression that both would regard a BlackBerry as the fruit that Peter Rabbit was on his way to gather when he got into mischief. And if either has succumbed to e-mail or a mobile phone, they don't admit it in their published letters.

Leigh Fermor, in one of the sudden moods of melancholy that occasionally punctuate his roaring boy ebullience, telephones the Duchess, but she is always out. The Duchess rings Leigh Fermor once and finds him in, but is disconcerted when he answers in Greek. Handwriting is the natural medium of their friendship, which rapidly gathers intimacy, from “Dear Paddy Leigh Fermor”, in 1954, to “Darling Debo”, in 1956.

Approaching this substantial and beautifully edited volume, the sensitive reader may find himself gripped by a vague sense of misgiving. Not shyness, exactly - after all, the two parties are still alive and writing, and are evidently happy for the rest of us to rustle through their private letters. Sir Patrick, the editor tells us in her introduction, has even “polished” his side of the correspondence.

Perhaps the fleeting unease has more to do with the status of both correspondents as national treasures, figures of near-myth: the Duchess with her great house, her hens and her unquiet flock of Mitford sisters; the knight with his hoard of chivalrous exploits - the great walk across Europe, the audacious wartime kidnapping of the Horace-quoting Nazi general; the swimming of the Hellespont. These stories are so well-publicised, so thoroughly venerated as to have taken on the glossy, impermeable quality of myth. Of course, it is the property of myths that they will bear any amount of retelling. But still ...

Anyway, it turns out that there is little cause for alarm. The literary ambitions of the correspondents are ill assorted - the Duchess claims to loathe reading and, when incautiously admitting to having read a book (Bruce Chatwin's On the Black Hill), hastily adds that it was so good that “I've never really felt like another”, while Leigh Fermor's letters - ornate, fantastical, embellished with drawings and poems - are sometimes conscious first drafts of material that will later be refined for publication.

But in other ways they are well matched. The romantic love of Leigh Fermor for the eccentric grandeur of country house life is nourished by visits, not so much to Chatsworth but to Lismore, the Devonshire's Gothic castle in Co Waterford, Ireland, while the Duchess's narratives of county shows and shooting parties are interrupted by high romantic dramas of her own, including a visit to the presidential inauguration of John F. Kennedy (“I had a v nice letter from Jack Kennedy, signed Yours ever Jack Kennedy and then below in his own writing President J.F. Kennedy, The White House, Washington DC, USA. Well I must say ... I had heard of him AND his bonne addresse ...”)

Marvellous as the great set-pieces are, it is in their more intimate moments that the real charm of these letters is to be found. Both correspondents are natural storytellers, and there is between them something of the quality of a practised duo of jazz musicians, jamming. So that from Leigh Fermor's brilliant comic account of two old Greek shepherds discussing the possession of a girl by a demon in the form of “a small black dog with one eye in the middle of its forehead”, or the Duchess's equally sparkling account of the installation at Chatsworth of an Elisabeth Frink bronze of a life-size heavy horse (“sort of Percheron type, Géricault-like bottom ... not the sort of thing you rush out and buy before breakfast”) there rises, not the sense of two separate personalities in dialogue, but of the single entity that is their friendship. The effect is intensely touching.

As the decades pass, friends fall away and what Leigh Fermor calls the Organ Recital of failing body parts becomes the preamble to every conversation, the letters take on an elegaic tone, but even then the high spirits and fine power of observation remain irrepressible. The final photograph in the book is of the pair, elderly now, walking companionably away from the camera, side by side. But that valedictory image is contradicted by the last two letters, Leigh Fermor's describing the olive harvest, “with lots of children and dogs skipping about, and pillars of pale blue smoke from the sawn-off branches floating up into the autumn sky”, while the Duchess recounts the perilous journey of a “daft mallard” and her 11 newly hatched ducklings across a ha-ha, a park and a main road towards the river. “I know it happens every year,” she writes, “but do admit the power of instinct.” Life goes on.

In Tearing Haste: Letters Between Deborah Devonshire and Patrick Leigh Fermor
John Murray, £25 Buy the book

Extract

April 26, 1955

Dear Debo,

I've just heard from Daphne on the point of departure to stay with you. Why does everyone go to that castle except me? ...

My plan is this: there is a brilliant young witch on this island (aged sixteen and very pretty), sovereign at thwarting the evil eye, casting out devils and foiling spells by incantation. It shouldn't be beyond her powers to turn me into a fish for a month and slip me into the harbour. I reckon I could get through the Mediterranean, across the Bay of Biscay, round Land's End and over the Irish Sea in about 28 days (if the weather holds) and on into the Blackwater. I'm told there's a stream that flows under your window, up which I propose to swim and, with a final effort, clear the sill and land on the carpet, where I insist on being treated like the frog prince for a couple of days of rest and recovery. (You could have a tank brought up - or lend me your bath if this is not inconvenient - till I'm ready to come downstairs. Also some flannel trousers, sensible walking shoes and a Donegal tweed Norfolk jacket with a belt across the small of the back and leather buttons.) But please be there. Otherwise there is all the risk of filleting, meunière etc, and, worst of all, au bleu ...

Please give my love to Daphne if she's with you. You can let her in on this plan, if you think it is suitable, but nobody else for the time being. These things always leak out.

Love

Paddy

P.S. Please write & say if this arrangement fits in with your plans.

April 30, 1955

Dear Paddy LF,

I was v v excited to get your letter with the swimming plan in it. It is a frightfully good plan, but the pestilential thing is that you would find, not me, but Fred Astaire installed in this pleasant residence. However if you could swim a bit further to the right and land in England and then be like an eel & get a bit across the land you can have the freedom of my bath in Derbyshire & I will have the sensible shoes etc ready.

I would like it like anything, so have a try and I will instruct any salmon around your route to see that you aren't filleted or meunièred or bleued.

I heard they set on you at a ball and broke you up, oh it was a shame.

Is it jolly in Greece? I bet it is.

Love from

Debo

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