O happy breed!

As I remember her, from decades ago, she always arrived rather like a broomless witch. Through a window, you'd have sworn, having careered downward from goodness-knew-where.

Her hair, even in the mildest of airs, flew every which way from a loose bun - skewered precariously by a bony comb carved for her, it was said, as a parting gift from a remote tribe assumed (until she passed some months with it) to be extinct.

The clothes she wore, or her manner of wearing them, reinforced a general impression of cavalier haphazardness. Only just attached to her rangy frame, they could appear to have been donned inside-out or the wrong way around, back to front. Moreover, every costume, whether of safari-khaki cotton or Scottish tweed - or a musky maroon velvet dredged up (one liked to fancy) from the sort of brass-ribbed trunk that Anna of Siam presumably sallied forth with - was complicated by the addition of a capacious pocket, sagging with what could prove to be almost anything....

Her nephew who, by his own account, had doted on her ever since ''like a gala gale'' she'd blown into his nursery, was a veritable treasure-trove of pocket-stories:

Once, for instance, she turned up, uninvited, at a reception being given by him and his wife, Flavia. Formally introduced to the guest of honor - a newly arrived ambassador from one of those tinier, and touchier, ex-colonies only recently celebrating its independence - she at once plunged into a pocket and brought up a nut. A single nut. ''It's from Brazil,'' she told him, speaking with the extreme delicacy of one acknowledging amid corn equally alien to them both a rapprochement hardly, under the circumstances, to be divulged more openly. You'd have thought (since he came from a quite other hemisphere) that the ambassador, suspecting some deep-laid insult, might well have taken umbrage. But no! Not a bit of it! ''In a twink,'' said the nephew, ''he was himself pocketed. To this day, I can never run into the dear chap without his in-stantly inquiring 'How is your Auntie?' ''

Then a certain dinner party: rendered august by the presence, in full rig, of an Ecclesiastical Personage. Here at a board justly famed for its excellence, she suddenly produced - wrapped in tinfoil - a large cold croquette made of mashed-up parsnips, lentils, and sundry highly aromatic herbs. To the disciplined company, momentarily riveted, she simply said, ''When it comes to venison, one's obliged to draw a line.'' ''It was really rather splendid,'' the nephew assured us. ''Quite a Luther ring to it.''

By the time I actually met her, she'd already become a legend - with all manner of outsiders chipping in to embellish it with contributions of their own:

The public meeting, for instance, when a young man espousing a thoroughly humane cause nervously lost his bearings at a crucial point. As he stood there on the platform, stricken speechless, she toweringly rose, all six feet of her, and encouragingly cried out, ''Hip, hip, hurrah.'' Then, flinging up an arm that almost smacked through the ceiling (the rented hall being a modest one), she briskly summoned the small audience to pitch in likewise.

''Hip, hip, hurrah,'' they straightway chorused. As if mesmerized, collectively, by a sharp Nanny-echo from London nurseries all the way from Belgravia to Hampstead....

Still another time (inevitably) she was found on a soapbox in Hyde Park: self-deputizing, it seemed, for a rather frail evangelist with streaming silver locks who was being subjected to the raillery of a certain ribald element in his ring of listeners. ''Naturally,'' she at once adjudicated - with all the ease of one who had been (for decades) straightening out for others their tangled webs - ''no one's obliged to agree with whatever it is our friend's trying to say. But when somebody really cares - and you do care, don't you? -'' to the open-mouthed recipient of this windfall from heaven, ''then it behooves us, in common decency , to grant him a fair hearing. Now then, Dad -'' here stooping a bit from her alarming height, ''let's have a go, shall we, at coming to the nub.''

Needless to say, she was herself sublimely capable of addressing anyone at all. As when a member of her family received one of those mixed-bag New Year Honors from the hand of the Queen. Belatedly hearing of this (at the time she was somewhere in the South Pacific with a small yachtful of protesters dedicated to the halting of something nefarious), she at once - the story ran - scribbled off a missive to Buckingham Palace.

''It is my special pleasure, ma'am, to be able to assure you, firsthand, that nobody could deserve this more than dear Basil. Even as a tot he was the soul of honor. Once, for instance, without being in the least suspected by any of us, he voluntarily owned up to having swallowed a pearl of mine.''

Inevitably such a saga was bound to include numerous hair-raising accounts of her riding a donkey through the wilds of Turkey. (This before it became a commonplace for the aunts of such a striking number of British authors similarly blessed - from their own tot-hood - with gold mines of dottiness to be drawn upon professionally.) Apparently she was asked for in marriage by a pasha. Here encountering incredulity, the nephew reasonably pointed out: ''I expect he envisioned a breed of sons powerful enough to reconquer Jerusalem itself.''

That she'd decline was foregone. But with what admirable delicacy. For instead of awkwardly bringing up an already more-than-ample provision of ladies, sumptuously stashed away among all those cushions, she simply produced as a deterrent a formidable program of prior commitments. The most pressing of which (at that particular moment) appeared to require her presence in a Welsh village for the supervising of a Music Festival she had herself initiated. ''They're in direst need, Suleiman. Misery, despair - you can't think! And that ghastly coal dust, in the very pores of the soul. It'll do them a world of good to have a bang-up sing.'' A rather fey marchioness - doted on by the media for popping about, like a fairy queen, in billows of mauve tulle - had already been bagged to perk up the Opening. ''Of course, she can't carry the simplest tune. But in any kind of pinch,'' with the offhand realism of an old pro, ''her smile's invaluable.''

Her own scrupulous adherence to any pledge once given could be testified to by a legion of beneficiaries. Even if her actual timings were apt to prove a bit sketchy. As when dressed to the nines (even sporting, at a rakish angle, a rather tarnished tiara with half its gems missing) she turned up for dinner on a Tuesday evening. A Tuesday three weeks earlier, it should have been. Showing no awareness of anything amiss, she simply observed, with a touch of tartness, ''I suppose the others are put off by a clap of thunder.''

A phenomenal storm was in process, doing untold damage half across the United Kingdom. Again needless to say, a misbehaving Nature was as little deferred to as the tantrums of an infant in a monogrammed pram. Come hurricane or avalanche, tidal wave or lava pouring from a cone, a ramrod nursery-code held fast. As indeed it did for anything at all - from gamely finishing up, to the last grain, a loathed rice pudding to not making a fuss if one crashed out of a tree.

All this has leapt to mind with the arrival of a letter. From England, naturally. Where else?

''An aunt of mine may be looking you up. There's no telling exactly when, or even how. Also, be warned, quite possibly she'll have in tow some kind of escapee. ... Not to worry about meals. She eats no creature, fish, flesh, or fowl; even snails she can refer to as her little brothers. If there's simply something gritty she can mix with her raisins. ... Her name's Laeaticia, by the way. But for all of us, when children - we adored her of course - she was Aunt Lettuce and still is. Actually, in The Great War, she was something of a Heroine , later decorated by the French government for having parachuted down on perilous missions. The family was dumbfounded! That she'd landed, I mean, where she was supposed to. In the nursery we assumed that, single-handed, she'd brought down Hitler....''

Perhaps that's how she'll come to us. Calmly floating out of the blue onto our nearest Alp. Or bolting from a shadowy forest, with some character at her heels gratefully crying ''I'm free - I'm free.''

Ah dear Aunt Lettuces! Unique. Irreplaceable. Almost gone.