There are all kinds of misconceptions about wine – many of them wilfully promoted by the people who make the stuff, and by lazy wine-writer who merely copy what they have read elsewhere. Which is why I thought it might he a good idea to dispel some of these illusions. And to reveal a few hard-to-believe facts about wine that are guaranteed to be authentic.

Sherry lasts indefinitely
The sweeter styles will keep but, even before you pull the cork, dry fino and manzanilla sherries may have lost their original, tangy freshness. So avoid leaving the bottle hanging around before you open it – and drink it up within the week. If you are likely to take longer than that, either pour half the sherry into a half-bottle when you first open it – or, wiser still, buy it in a half-bottle in the first place.

Sherry, port and Champagne can be made anywhere
In the USA, though not in Oregon where stricter rules apply, all sort of cheap fizzy wine can call itself Champagne. In Europe, however, reasonable EC regulations forbid the sale of “Champagne” made anywhere outside the French region of that name. Likewise, genuine sherry only comes from Spain and port from the Douro in Portugal.

Canandian, Japanese and British wine is made from grapes grown respectively in Canada, Japan and Britain

Canada and Japan traditionally make wine from their own grapes but also import grape concentrate from South America and bottle it as local produce (Ontario and British Columbia both grow wine grapes but “Quebec wine” all almost certainly come from a long way further south).

“British” wine – unlike English wine (which confusingly includes Welsh wine) is actually produced by a British technique of diluting and fermenting the grape concentrate which, in this instance, tends to come from Cyprus.

In fact, under European law, none of these reconstituted drinks is defined as “wine” which, by the EC definition, has to be made from freshly picked grapes. English wine is real stuff – though even this is allowed to contain a little sweetening juice from Germany.

Red Bordeaux is made from the Cabernet Sauvignon
Well, quite a lot of it is – but actually, the Merlot is the most widely planted grape in Bordeaux. And in the communes of St Emilion and Pomerol, the blend is often just Merlot and Cabernet Franc.

All wines improve with age
This is a belief still common in the countries of southern and eastern Europe and South America, where older wines are thought to be better by definition and people have become used to drinking wine with the taste of oxidation – the sherry-like character of wines that are past their best. Most modern wine-drinkers now prefer wines with fresher, fruitier flavours. Almost all inexpensive white wines should be drunk within a couple of years (at most) of the harvest, and even Bordeaux may need drinking young in vintage.

Cheap wines don’t travel
Some don’t – but then again, nor do some frail, old, expensive ones. In the case of young, cheap wine, everything depends on the way it has been produced. Well-made wine, whatever its price, should have no difficulty in being carried from one side of the world to the other. When a wine you enjoyed on holiday and brought back with you doesn’t taste quite the same at home, it’s very likely to be because the circumstances have changed, not the wine.

Great wine can never be made in stainless steel tanks
Some of the best chateaux in Bordeaux ferment their wine in stainless steel nowadays – and make better wine than ever.

The word “chateau” indicates quality
It certainly does no much thing – however smart the label. Any wine estate in France can call its building a chateau (even if it is little smarter than a garden hut) and, in Bordeaux, almost every estate will do so. To complicate matters still further, some co-operatives use a loophole in the rules to put “chateau” labels on wines they make.

Great wines are never blends; they always come from specific vineyards
What about Champagne like Krug and vintage port, both of which are almost always blends? And what about Grange, the Australian red which has, since its creation in the 1950s, always been a blend from several regions of South Australia?

“Legs” are the sign of a better wine
What the French call the “legs” – and what the Germans call “cathedral windows” – are the streams that flow down the glass once you have swirled the wine around. These are often thought to mean that the wine is especially good. All they really indicate is that the wine is rich in glycerine and was thus made from ripe grapes. Even ripe grapes can be turned into bad wine.

All Rieslings are basically the same grape
The grape of this name grown in Germany and Alsace is the only one of any real quality. When it’s grown elsewhere, it is often called the Johannisberg Riesling or the Rhine Riesling to avoid confusion with the completely unrelated and inferior Laski, Welsh and Italico Rizlings. And the grape the Australians used to call the “Hunter Valley Riesling” is actually the Semillon.

Beaujolais Nouveau has to be drunk by Christmas
There is technically no difference between Beaujolais Nouveau and the kind of Beaujolais we all drink during the rest of the year - except that it is sold earlier. It is usually best drunk quite young, but good Nouveau from one of the region’s better producers and vintages can be delicious – and sometimes even better – a year after the harvest.

Screw-top bottles are not as “good” as corked bottles
They are certainly less romantic, but numerous tests have proved that they are far more effective and eliminate the risk of corkiness.

You can always tell a corked wine by smelling the cork
Sometimes a musty-smelling cork will warn you that a wine is faulty; quite often, however, the cork may show no signs of deterioration at all. The sure way to tell a corked wine from a dirty, or otherwise faulty, one is that it will actually smell and taste worse the longer it is in the glass.

All red wines improve with decanting
Some do benefit from the airing they get by being poured from a bottle into a decanter, but less full-bodied wines – such as red burgundy – can lose some of their fruit by being manhandled in this way.

As a general rule, the only wines that need to be decanted are the ones that have a heavy deposit – all vintage port, most mature red Bordeaux, old Rhones, Barolos, Australian and Californian reds, for example.

Brut Champagne is bone-dry
It tastes dry; in fact, all Brut Champagnes are slightly sweetened. If you want a bone-dry fizz, go for Brut Zero or Brut Sauvage, which have “zero dosage” – no sweetening at all. But I’ll lay money that you’ll probably prefer the Brut.

A good vintage in Bordeaux is also good in Burgundy
There two regions are separated the mountain range, the Massif Central, and enjoy completely different climates. In 1982, Bordeaux had a historic vintage for its rd wines; Burgundy’s reds were pleasant but far from great. Beware too of assuming that vintages are of consistent quality for all the styles produced in a single region. Burgundy’s white wines were far better in 1992 than its reds; 1967 Sauternes were wonderful; the red Bordeaux of that year were often little short of appalling.

A hot summer means a good vintage
A cold, rainy summer and autumn will usually make for a bad year, but a hot month of August will not necessarily indicate a good one. Vintages depend on the weather being “right” at various phases of a grape’s development, from the spring to the autumn. A late storm at the end of September can spoil what, at the beginning of that month, seemed set to be a great vintage.

Qualitatswein, Appellation Controlee, DO, DOC or DOCG on a label are a guarantee of quality
They should be; unfortunately all these expressions legally indicate only that the producer has ensured his wine conform to a set of controls governing grape varieties, their origin and methods of production – not that he has to be a good wine-maker. Hence they can only really serve as a guide to what the wine is going to be like.