The barleycorn, for example, has a long history in Great Britain as a unit of length. It’s equal to a third of an inch, or around 0.8 centimetres, and has been associated with length at least since the early fourteenth century, when King Edward II declared that ‘three grains of barley, dry and round make an inch’. This definition later became standardised in the imperial system of measurement, and is still in use today as an increment in UK and US shoe sizes. The difference between sizes is equivalent to a third of an inch, which shoemakers call a barleycorn.
