Je ne connais rien de sérieux, ici-bas, que la culture de la vigne.
It is advisable to buy your wine from a reputable wine merchant; you are more likely to obtain the genuine article than at the next door grocer’s. After all, there is no reason why an English grocer should know anything about wine.1
In any case, never buy wines labelled ever so vaguely Beaune, Pommard, St. Julien, St. Emilion; these names mean nothing, and the labels no doubt cover a multitude of doctored wines. If you do not know anything about it, and cannot afford chateau-bottled wines, let your wine merchant advise you about his cheaper vintages. It is in his interest as well as yours.