The undeniably convenient screw cap is rapidly replacing natural cork as the preferred closure for wine. Almost 70 per cent of all wine sold now has a screw cap. Though in France it is still hard to sell a screw-top wine, here in Great Britain it is getting harder to find natural cork in the mid-price range.

In Australia, the screw cap has won the field almost entirely. Penfolds, for instance, has used screw caps on all white wines since 2004 and the same is now happening to its reds (though, significantly, its highest-priced red, the legendary Grange, successor to Grange Hermitage, is still sealed with cork).

Cork has always been the Achilles heel of wine production. Winemakers go to enormous lengths to ensure the quality of what goes into the bottle; but it is then entrusted to a piece of tree bark from the cork oak, or Quercus suber, whose reliability cannot be accurately tested and whose behaviour and durability is impossible to predict. Though the contents of about 92 per cent of bottles survive being sealed with cork, one in 12 does not.