The cork and elaborately engraved stopper on some luxury whiskies can end up costing you £3 or more, the cork itself has come on a fascinating journey and deserves your attention.After all, it does an important job, quietly and well, and actually plays quite a role in keeping your whisky in peak condition.Oh, and it sounds great, doesn’t it? When you pull it from the neck of the bottle. What pleasures are hinted at in the simple, gentle pop of a cork.If we step back into history, the driven cork (like the cork on today’s wine bottles) was the standard closure when bottles first arrived on the whisky scene. But this required a corkscrew and was tricky to reseal. Moreover, as whisky sales grew round the world, problems developed with corks shrinking in the heat of markets such as India and new closures were adopted.One of the first was the spring, or lever cap introduced with some fanfare by Dewar’s in 1927 and widely taken up by a grateful industry and consumer. Today’s screw cap arrived during the 1960s and has been the dominant closure ever since.But the cork is making a comeback, and today is the closure of choice for most single malts and premium blends. It does add a touch of luxury and quality, after all, and as it comes from an oak tree is whisky’s natural closure.Quercus Suber, the cork oak, is native to the Western basin of the Mediterranean with around 25,000 square kilometres under cultivation. More than half of the trees are found in Portugal, where I visited the spectacular Alentejo cork forest with Amorim, the world’s top producer of quality cork.Cork trees can live for up to 200 years and, after the 25th birthday, can be safely harvested of their remarkable bark every nine years or so. So this is truly a natural, renewable resource that speaks to our current concerns for the environment and bio-diversity.Did you know, for example, that the Portuguese cork forest, protected by government decree, is home to more than 700 species of wildlife, many of them threatened or even endangered? Among the animals found in the forest are the lynx, wild boar, wildcat, genet, fox and hundreds of varieties of birds and smaller mammals.They find a sanctuary in the forest and are protected from hunting or urbanisation.As the Worldwide Fund for Nature concluded in a recent report: “Cork oak forest landscapes are maintained and restored, supporting economically viable and culturally and socially beneficial multi-purpose management systems. “This leads to sustainable livelihoods and improved bio-diversity.” Even more significant, given today’s concern with global warming, is that the cork forest plays a major role as a CO2 sink, with the Portuguese cork forest alone capturing 4.8 million tonnes of CO2.And cork can be recycled. In fact, Amorim has been one of the leaders in an educational programme being tested in Portuguese schools and supermarkets to collect old corks for recycling. If it works, it may not be long before you are recycling not just your empty bottles but the cork as well.The production process from cork forest to distillery bottling line is a fascinating one, with a bewildering number of steps to ensure quality control and consistency in the finished article. The cork, once stripped from the trees by highly skilled gangs of workers, is boiled, cleaned, trimmed, punched, dressed and polished. It is caressed both by machine and human and watched over by a R&D department staffed by PhD-level scientists, all bent on bringing you a better cork.All of this was brought about by the problem of TCA contamination in cork, which results in ‘corked’ wines and an ‘off’ flavour in spirits. A naturally occurring phenomenon, TCA was a major problem for cork producers and a boost for the screwcap.But the resilient Portuguese are fighting back and have enlisted cutting-edge science to defeat the problem. The investment has been staggering: suffice it to say that throughout Amorim’s forests and factories stainless steel pallets are used to transport all the cork to guard against the (tiny) potential risk of TCA contamination from wooden pallets. The cost of all this is immense, but the stakes were huge: potentially, the death of a traditional industry and a part of Portuguese culture and national heritage.And, once it gets to the bottling line, cork’s real work is just beginning. Cork itself consists of a honeycomb of small cells, each filled with an air-like gas – and there are nearly 800 million of these cells in a single cork stopper. Remarkably, the cells can be compressed to half their size without losing flexibility and they have an ‘elastic memory’, that is to say they are constantly trying to return to their original size and shape.This means two things: an even pressure on the neck of the bottle, and thus a good seal and a high level of tolerance to changes in temperature and pressure. As a result, your precious whisky is kept in near-perfect condition but requires the minimum of effort to open, time after time.As we’ve seen, the sound of a popping cork helps us anticipate the delight to come.But, if that isn’t good enough, remind your fellow drinkers that the simple cork protects the environment, saves endangered wildlife, is part of a cultural tradition dating back to ancient Egypt and can be recycled. In fact, it’s a very PC closure.