Blended Scotch whisky, or 'Scotch', is by far the world's most popular whisky and accounts for well over 85 per cent of all Scottish whisky.
'Malt whisky' was the original Scottish whisky, and although it has recently become extremely popular, the majority of malt whisky is still sold in blended whiskies, not as 'single malt whisky'.
The practice of adding the newly available grain spirit (due to the development of the column still) to pot still malts was unofficially first practiced by publicans to increase their profit margins in the early 1800s. But it is Andrew Usher, an Edinburgh a wine and spirit merchant and the local agent for the Glenlivet distillery, who is credited, in 1853, as being the first person to experiment with different combinations of whiskies of varying ages to create the first blended whisky.
The Spirits Act of 1860 made it legal for the first time to blend whiskies from different distilleries before duty was paid. Usher took advantage of this and began marketing a vatting (blending) of Glenlivets under the brand name Usher's OVG (Old Vatted Glenlivet). He soon begun to cut the cost of his blends by including cheap grain whisky which also had the happy effect of making his blends smoother.
The pot still malts available until then had struggled to compete outside Scotland with the lighter, triple distilled Irish whiskies. Usher realised that by blending pot still malts with grain whisky he could create whiskies that, while flavourful, would be less challenging and have greater commercial appeal.
Andrew Usher's lead popularised Scotch whisky in England and many famous early pioneer blenders followed - many of these now famous names owned grocery shops and created blends to be sold to their shop's clientele. They included: Arthur Bell (Bell's), Alexander Walker (Johnnie Walker), John and Tommy Dewar (Dewar's), James Buchanan (Black & White), Thomas Sandeman (Vat 69) and Peter Mackie (White Horse).
When the phylloxera aphid annihilated Cognac's vineyards in the 1880s, Scotch whisky took cognac's place in the international market as the premium spirit of choice.
Like cognac, the quality of Scotch is reliant on the blender's ability and experience to select from the ever-changing casks available and skilfully blend them to match the style of the brand time after time, providing the drinker with a consistent product. Although the style of a brand may vary over the years, this is generally due to a conscious decision to improve it or to suit changing tastes.
A standard blended Scotch whisky will probably contain 15-40 per cent malt and have no age statement (though every whisky in it will have been aged at least three years). Some blends describe themselves as 'deluxe' - this is a reference to the percentage of malt whisky in the blend and the average age of the whisky. A deluxe brand will usually contain more than 45 per cent pot still malt and show an age statement of 12 years or more.