Primeurs? Early-season vegetables, aren't they? Nimble little lace-leaved carrots; rows of radishes lined up in a box like toy soldiers; pink-blushing turnips barely bigger than chestnuts, trundled through the night to Rungis and le ventre de Paris from the Loire valley's softest river silt.

Not any more. Nowadays the word tends to mean wine-merchant's invoices carefully locked away in a desk drawer. It signifies a vision of neat wooden boxes stamped with the name of Bordeaux châteaux; and it equates to the wine world's perfect business model, envied by producers everywhere. Thus the world turns.

In some ways, the success of 'en primeur' (or pre-arrival) wine sales is surprising. The wines, after all, are sold in an unfinished state, lying in barrels, when the eventual blend for the finished wine may be no more than a set of calculations on the back of an envelope, and with the traumas of bottling and shipping still to come. The possibilities of fraud or mishap are numerous: if en primeur sales are good, the proprietor might be tempted to make a little more grand vin than he originally thought; the samples shown to the wine press may have been unrepresentative anyway; crass fining and filtering may rob the wine of the modest but pert charms it shows in barrel; and the wine merchant banking your cheque may sink haplessly into the liquidator's arms before your wine is ever shipped. I have personal experience of the last two occurences, and strong grounds for suspicion of the two former.

As a coldly calculated investment, too, the vast majority of wine sold en primeur over the last decade will have performed dully or poorly, and in most cases the purchasers would have done better to buy three or four years later, when early tastings of the bottled wines reveal the truth about their qualities. The price for most wines tends to glue for around five years once the en primeur flurry has died down; some then slide slightly, as subsequent vintages prove sexier. All of this, wine writers are honour bound to point out; but most writers dislike en primeur, too, because the market is made by the American critic Robert Parker's scores, and their own passionately held convictions about the wines empty as tracelessly into the waiting air as a bottle of mineral water does into the ocean.

After the fiasco of 1997 (when all en primeur purchasers lost money) and desultory campaigns for 1999, 2001, 2002 and 2004, the death of the system is often said to be imminent. Yet the 2005 campaign has just broken all records. Farr Vintners had doubled the value achieved with the 2000s by the end of June; Berry Bros & Rudd has beaten its record 'by some margin'; and Mark Bedini of Fine and Rare Wines, sticking to the military metaphor, describes it as 'shock and awe'.

'There's so much money around we've had a queue of people for almost everything,' says Bedini. "We sold three times what we sold in 2000, and we could have sold more. One purchaser only bought in lots of five cases and complained when we could only get him one case of Latour. We've never seen anything like it."