It should be the most sought-after drink in the world, given its rarity: it should be up there with unicorn tears. For there are, today, only five little bottles of Snowball remaining in the world. Two of them have been sitting, since the spring of 1978, in the lower shelf of an oak cabinet in the guests' dining-room in the boarding-house of one Miss Mavis Plankton of Porthcawl, in case there's a sudden rush from the continent: the other three lie forgotten inside an attic trunk in the home of a wife-swapping couple from Kidderminster, along with a spring 1978 issue of Knave, a book of fondue recipes and a Betamax tape of an episode of The Goodies.

It's an astonishing fall from grace for a drink which was once, briefly, though not nearly briefly enough, the drink of choice for the jet set, when that phrase could be used without recourse to an ironic typeface. During the Seventies, when Gstaad was home to endless cavortings of the rich, beautiful and gothically stupid, this mix of advocaat and lemonade was, for a season or three, the in-thing: and, of course, as soon as the social class which psephologists describe as 'prole scum' got to hear of it, they wanted some of their own: and, of course, class being what it is, the whole thing went pretty quickly downhill, and the snowball soon became irredeemably associated with Seventies naff, and it died on the same April 1977 evening in which the rest of the Seventies began to die, when we watched Abigail's Party, and is now consigned to history along with Athena posters, Spangles, wife-swapping and Kidderminster.

Which misses the point. It should be forgotten not because of some sociological accident but because it is fabulously noxious. Advocaat is, it says on the label, made by doing something terminally cruel to eggs and letting the results sweat for a while and sticking them inside a bottle: but this wholly fails to capture the horror. If you can imagine making a glass of banana Nesquik, then letting it stand in the corner of a warm room for 14 days, quietly fermenting and curdling at you all the while, like a vicious little yellow rebuke, then straining the results through a piece of muslin which has been marinaded for a couple of months in a meld of lark's vomit and brine, then shaking a tramp by the feet and taking all the things that drop from his groin and ears and whisking them in for texture, you have only then begun to imagine the filthy misery of a snowball. We yearn for the snowball like we yearn for rickets.