DRINK Avoid dusty bottles, and especially any with faded labels. And never buy any drink from a shop window
It was presented with panache. At the top table was fragrance consultant Tom Richardson, who works for the likes of Calvin Klein. With him was Samuel Twining, representing nine generations in the tea business. There were also a couple of whisky blenders. In the audience, on gilded chairs in a Georgian house in Knightsbridge, were 50 of the most distinguished judges of aromas and drinks.

The occasion was a ceremony. Macallan had bought, at an auction, a pounds 4,000, 1874 bottle labelled as their own whisky. The guess was that the whisky had spent 20-odd years in the cask and a century in the bottle.

In countries where old whiskies are greatly valued, such as Italy, some such bottles have been deemed fakes. Macallan's whisky-maker, Frank Newlands, had already inserted a syringe through the cork, taken a 10ml sample, and felt that he recognised the fruitiness that still characterises whisky from the famous distillery. Now, the bottle was to be uncorked, to be judged by the top table and gilded chairs. Frank held it over a silver bowl, in case the cork crumbled, but it came out with suspicious ease. We got 5 or 6ml each of the whisky.

Parfumier Richardson found orange, plum and melon. Sam Twining liked the woody pungency. One whiskey-blender detected lemon and lime, the other spoke of malty depth. I deemed it delicately flowery in bouquet and lean but toffeeish in palate.

Then Frank gave us another sample. Based on his original 10ml, he had tried to assemble a similar whisky from nine casks in Macallan's maturation warehouses. The oldest cask had seen 26 summers, and the average age was just under 18. A key element had been old whisky aged in fine sherry casks, rather than the dry oloroso favoured by Macallan for the past 25 years or so. Frank's "1874" whisky was universally agreed to be bigger in character, and I loved its flavours of ginger-cake and aniseed. A limited edition of 12,000 bottles is going in the fancier whisky and wine shops at pounds 75 a pop. In an unexpected historic twist, this will be the last bottling from Macallan as an independent enterprise: the company has just been snapped up by Highland Distilleries, in concert with Suntory, of Japan.

Why couldn't Macallan match the old whisky more closely? Because no drink or food can ever be the same as it once was, whatever the makers say. Different varieties of barley were grown 122 years ago. Each year's weather influences both the character of the barley and the procedures of malting, distilling and maturing.

More importantly, malt was generally given a more robust peat-drying then. Much of the industry has aimed for less smoky whiskies, believing that consumers want blander tastes (and, by such appeasement, encouraging the sales of vodka). As fewer distilleries have operated their own maltings, that significant element of distinction has diminished .

Everyone was surprised that the original 1874 Macallan was not more peaty and smoky. It could be that the easily-drawn cork had allowed some character to evaporate. It is often argued that change happens only in the cask, but that is not true.

Certainly, the big positive developments take place in the cask, though not indefinitely. Harsh flowers are breathed out and the local atmosphere, whether heathery or briney, inhaled. Oaky flavours, and perhaps traces of a previous occupant such as sherry, are absorbed by the whisky. Reactions involving traces of copper from the stills, oak and oxygen, create spicy, minty flavours. All of this may peak anywhere between eight and 20-odd years and occasionally later.

Once the whisky is in the bottle, none of these changes can take place, but flavours can meld - and liveliness can diminish. A bottle that has sat in a shop for five or 10 years will still be perfectly drinkable but may not be at its best. Avoid dusty bottles, and especially any with faded labels. If the whisky has been in the window, in sunlight, its colour may also have been bleached. Never buy any drink from a shop window.

Once the bottle has been opened, and especially if a substantial proportion of the whisky has been consumed, the influence of oxygen can cause the rest to fall apart. I was once given a bottle of New England rum, distilled in 1909 and bottled in 1927. I sampled it in the 1980s, then returned to it after several months to discover that it had assumed the colour of dishwater and a gritty, flakey, astringent taste bearing no relation to any alcoholic drink.

A gentleperson never re-seals a bottle. My guests will help me drain the new Macallan 1874 on the Glorious Twelfth next week. There will be no grouse yet - that needs hanging for a week or two

Whiskies of the week Speaking of old whiskies... Glengoyne has just released, at pounds 90 a bottle, a limited-edition Glegoyne1970 malt, made entirely from the classic Golden Promise barley, grown on one farm in Northumberland. It is deliciously creamy, with a suggestion of Cox's apples. And United Distillers will shortly release, at pounds 50-55 (70cl), another selection under the rubric The Rare Malts. These include an Aultmore 21-year-old with a hay-like bouquet; an expressive Benrinnes 21 (spicy, anis-like); a nutty (peanut brittle? fudge?) Craigellachie 22; and an apricot-tasting Glen Esk, the last from the stocks of a distillery now dismantled. More from this range will only be available duty-free at pounds 45-50 (75cl). These include a seaweedy, salty Brora 21; olivey, lemony Caol Ila 20; a chewy, heathery Glendullan 23; a perfumy (violets?) Dailuaine; and an aromatic (sandalwood, incense?) Teaninich 23