Whisky Johnnie Walker Blenders Batch Rum Cask Finish. Introducing Johnnie Walker Blenders Batch Rum Cask Finish. An experiment that saw the creation of a relaxed and easy going Scotch. This batch is a culmination of blender Chris Clark’s experimentation to create a whisky with smooth and spicy flavours. By finishing the whisky in casks which previously held Caribbean pot still rum, he developed a Scotch tingling with layers of exotic fruits, sweetness and a little spice.