Barley is the most important raw material in the production process. Quality malting barley is required for the malting process, allowing the maltster to produce a homogenous product that can be processed in the distillery. A distiller wants consistency in his raw materials (well, this one did anyway); he wants to be able to set up his process and produce a consistent product himself.
The variety of malting barley is important in terms of yield and processability but not in terms of character of the spirit; myth one busted!
Some distillers will tell you that they use this variety and that variety in order to get the flavour and character they require; not true.
Barley variety plays a negligible part in the formation of character and flavour. The quality of the malt, which can come back to the quality of the barley can have an impact, so in that sense a quality malting variety should be used, but the variety will not give you this flavour or that flavour. In my long career in the industry I saw two cases where allegedly a change in barley variety resulted in a change of character at a distillery (and I think one of these was due to malt quality rather than variety).
The source of malting barley is important in terms of quality and cost of logistics but not in terms of character of the spirit; myth two busted!
This picture shows a field with a distilling approved barley variety growing away happily and looking really good at that stage of development, and it is in France!
Some claim to only use Scottish barley, or imply that in some of their marketing, but the geographical location is unimportant. I agree that it is good for the Scottish economy to purchase Scottish barley (and I would love it if the distilling industry purchased as much malting barley as possible from home soil) but it is not essential in terms of flavour (and in terms of the legality of Scotch whisky). France, Denmark and, dare I say, even England produce excellent malting barley, with a number of European countries starting to grow malting barley varieties specifically for the Scotch whisky market. Do you like a good Islay malt? Well then, there is a good possibility part of it was made from Norfolk malting barley!
It is a myth that barley variety is important in terms of character and flavour, my next myth buster will talk about water!