Launched in 2017 and titled 'Mastery of Oak', this is the fourth bottling in the John Walker & Sons Private Collection series. Johnnie Walker master blender Jim Beveridge, together with the help of fellow blender Aimée Gibson, handpicked casks of malt and grain whiskeys to create three vattings, each selected for their ability to display different oak characteristics. The first vatting is a selection of grain whiskies, plus one malt, all aged predominantly in first-fill American oak casks; the second vatting consists of single malts from the Highlands and Speyside aged in refill casks; and the third vatting consists of “experimental” malt and grain whiskies aged in American oak casks (which feature different char profiles, housed different drinks beforehand and some had even been "salt cured"). A total of 5,588 individually numbered amber glass decanters were produced. Bottled at 46.8%.

Nose: Toffee, vanilla and ripe orchard fruit notes that translate on the palate.

Palate: Dark berries, soft peach skin and stewed apple flavours also emerge, with a hint of green apples from the refill casks and leather from the European oak casks.

Finish: Experimental oak casks give the whisky a deep, rich vanilla finish.