A subtitle on the label reads "The Solera Vat." The word solera is borrowed from the sherry world, a reference to the system of fractional blending in which a wooden vat or cask is partly drained, to be refilled with a younger vintage. Because the contents are always mixing around, the proportion that's tapped off represents a marriage of very old as well as younger whiskies. Glenfiddich drains off about 50-per-cent of the liquid for this bottling, which contains whiskies of at least 15 years of age that had previously spent time in casks once used for sherry and bourbon as well as newly coopered oak. The technique, which yields a slightly different profile from bottling to bottling, is compelling when it comes to whisky as well as sherry. Deep amber in colour, this 15-year-old is markedly richer than the flagship 12-year-old, with a velvety texture carrying a luscious core of dried fruit, caramel, burnt sugar, honey and classic Glenfiddich pear in good balance with the underlying cereal grain, all set against an invigorating backbone of smoky peat.