The rules around single malts used to be pretty simple. The whisky was seldom if ever matured for less than a decade, and the age would be proudly displayed on the label. If you grew fond of a particular 12 year old, you might occasionally treat yourself to an 18 or 21 year old from the same distillery. Given the leap in price as you stretched back in time the message was clear: the older the whisky the better.

But that was when there was a feast of well-matured whisky lying in dank warehouses across Scotland. Now there’s a famine and many distillers are starting to abandon those once sacred numbers. Today non-age statement (NAS) whiskies account for at least a third of the malts in a typical supermarket.

The Scotch whisky industry is struggling to secure enough second-hand casks from bourbon distillers in America, and this has only increased the pressure on maturation times in order to free up the barrels. Besides which there is an obvious incentive not to age whisky for any longer than you have to given the 1-2% that evaporates every year in the angle’s share.

Most distillers are hedging their bets by offering whisky drinkers a single malt like Talisker Storm alongside the regular 10 year old. In time I suspect the latter will be withdrawn or raised in price to persuade us to embrace the NAS option. Macallan has dropped age in favour of colour starting with The Macallan Gold and progressing through Amber, Sienna and Ruby. The cheapest official expression with a number on the label is now the 18 year old at around £170.

It’s not age but maturity that counts, argue the distillers who point to the absurdity of waiting for some arbitrary birthday like 10 or 12. In the case of Macallan they will tell you it has nothing to do with any crisis in the warehouse, and is merely to release the creativity of the whisky maker and free him from the shackles of age. Call me a cynic, but I think they’re being disingenuous.

The fact is the industry has been a victim of its own success and it is the dearth of old, matured stocks that is driving the trend in NAS whiskies and nothing else. Sure the number on the label is a crude measure of quality at best, but it is a benchmark free from marketing.