There are two truly thrilling grape varieties: Pinot Noir and Riesling. Other grape varieties can produce great wine; they can be magnificent, impressive, beautiful, memorable, wonderful – all manner of things, but there is something about these two grape varieties that goes further than the rest. Interestingly, they are both very sensitive to vineyard sites, and reflect differences in soil, terroir, and so on. And they both perform best in marginal, cool climates.

  Of course, in other respects they are very different – for a start, Riesling is a white grape. Its home is Germany, reaching its finest expression in the vineyards along the Rhine and its tributaries the Nahe and Mosel, and in turn the Mosel's tributaries the Saar and Ruwer.

  Just to clear up one point: there are a number of grape varieties, such as Welschriesling, Cape Riesling, Laski Rizling, Riesling Italico and so on, which are not Riesling at all. They are all (inferior) varieties which produce flowery-flavoured, aromatic wines that display some of the taste characteristics of true Riesling. My advice is to stick to Riesling proper. In fact, further, if you're buying German wine, only buy Riesling; it is far and away Germany's best grape variety, so why bother with any other? I don't – all the German wines I stock in my shop are Rieslings.

  Sadly, the British market for years was swamped by cheap, mass-produced German wines, which probably, though not necessarily, contained at least some Riesling, such as Liebfraumilch, which were faintly alcoholic sugar-water. I'm not sure I'd call them wine at all. They were very dull and turned the public off German wine almost terminally. Fine Riesling is nothing like this: it has a thrilling, vital acidity that combines with brilliant, fresh, fascinatingly aromatic fruit that produces tastes that may be flowery, steely, mineral, honeyed, citric, and, in aged examples, oily, petrolly (which is very pleasant!); it may be anything from bone-dry to lusciously, viscously sweet – but always with mouthwatering acidity. For me, the finest, most satisfying wines are sweet but not too sweet – in German wines they will say either Kabinett, Spätlese or Auslese on the label. Drier styles do not on the whole suit the grape, though the Australians are producing this style very successfully. And the sweetest styles are just a bit too much for my taste – and very expensive.

 Another feature of the grape is that the wines have extraordinary longevity, and develop the most wonderful flavours of petrol, flowers and spice with age, always supported by beautiful acidity that keeps them fresh and drinkable almost indefinitely.

  Riesling is now grown around the world, with plantings in California where its most successful manifestation is as a late-harvest sweet wine, Australia where, as stated above, the producers have developed a fine dry style, particularly around the Clare Valley (Jeff Grosset produces outstanding bottles), New Zealand, and Alsace in France, where it is usually dry, but can be made sweet ("Vendanges Tardives" and "Selection des Grains Nobles").